Transcript Continued

District Assessment Review
“We CAN be the Champions!!”
OBJECTIVE 1:
Compare and contrast speed, velocity, and acceleration.
Calculate speed, velocity, acceleration and momentum.
What is speed?


Speed is the distance traveled divided by the time
interval during which the motion occurred
It is a rate.
What is the equation for
finding speed?

Speed (or Velocity) = Distance or v = d
Time
t
What is velocity?


Velocity is the same as speed.
Velocity includes the direction of motion as well as
how fast the object is moving
What is acceleration?

Acceleration is the change in velocity divided by
the time interval in which the change occurred.
If a car accelerates from 0 miles/hour to 60
miles/hour in 5 minutes, the change in velocity
would be 60 and the time would be 5 minutes.

OBJECTIVE 1:
(Continued)
Compare and contrast speed, velocity, and acceleration.
Calculate speed, velocity, acceleration and momentum.
How do you calculate
acceleration?
 Acceleration = final velocity – initial velocity
What is an example
of a problem
involving speed,
distance and time?
Problem: If a car moves along a perfectly
straight road at 24 m/s, how far will the car go
in 35 minutes?
time
 Acceleration is positive if you are speeding
up and negative if you are slowing down.
 The units for acceleration are m/s2
Knowns: v = 24 m/s
Unknown: d = ? m
t = 35 X 60 = 2100 s
d=vxt
d
24 m/s
2100 s
24 x 2100 = 50,400 m
OBJECTIVE 1:
(Continued)
Compare and contrast speed, velocity, and acceleration.
Calculate speed, velocity, acceleration and momentum.
What is an example
of a problem
involving
acceleration,
velocity and time?
Problem: While driving at an average velocity of
15.6 m/s down the road, a driver slams on the
brakes to avoid hitting a squirrel. The car
stops completely in 4.2 s. What is the average
acceleration of the car?
Knowns: initial velocity = 15.6 m/s
final velocity = 0 m/s
time = 4.2 s
Unknown: a = ? m/s2
Acceleration = final velocity – initial velocity
time
a = 0 - 15.6
4.2
a = - 3.7 m/s2
OBJECTIVE 1:
(Continued)
Compare and contrast speed, velocity, and acceleration.
Calculate speed, velocity, acceleration and momentum.
How do you calculate
momentum?
 Momentum = Mass x Velocity or p = m x v
What is an example
of a problem
involving
momentum, mass
and velocity?
Problem: You are traveling west on your bicycle
at 4.2 m/s, and you and your bike have a
combined mass of 75 kg. What is the
momentum of you and your bicycle?
Knowns: m = 75 kg Unknown: p = ? kg · m/s
v = 4.2 m/s
p
p=mxv
75 kg
4.2 m/s
75 x 4.2 = 315 kg · m/s
OBJECTIVE 1:
(Continued)
Compare and contrast speed, velocity, and acceleration.
Calculate speed, velocity, acceleration and momentum.
The difference between speed and velocity is
that velocity includes __________.
A. acceleration.
B. time.
C. distance.
D. direction.
Remember:
d
v
t
Remember:
p
m
v
A runner, who has a mass of 53 kg, has a
momentum of 218 kg · m/s along a trail.
What is the runner’s velocity?
A. 12,000 m/s
B. 4.1 m/s
C. 0.24 m/s
D. 120 m/s
OBJECTIVE 1:
(Continued)
Compare and contrast speed, velocity, and acceleration.
Calculate speed, velocity, acceleration and momentum.
Natalie accelerates her bicycle along a
straight path from 0 m/s to 4.0 m/s in 2.5 s.
Find her average acceleration.
A. 1.6 m/s2
B. -1.6 m/s2
C. 0.63 m/s2
D. -0.63 m/s2
Which of the following objects is NOT
accelerating?
A. A ball being juggled.
B. AAwoman
woman walking
walking at
at 2.5
2.5 m/s
m/s
along
alongaastraight
straightroad.
road.
C. A satellite circling Earth.
D. A braking cyclist.
OBJECTIVE 2:
Determine speed from a distance-time graph.
Determine acceleration from a velocity-time graph.
How do we
determine speed
from a distance –
time graph?
 You can determine the speed by finding the
slope of the line.
 Slope = Rise (y2 – y1)
Run (x2 – x1)
 You could determine the speed of a
cruising jet by finding 2 points on the
line and then calculating the slope.
Example:
Point 1: (1 s, 200 m)
Point 2: (2 s, 400 m)
Slope = 400 – 200 = 200 m/s
2–1
OBJECTIVE 2:
(Continued)
Determine speed from a distance-time graph.
Determine acceleration from a velocity-time graph.
How do we
determine
acceleration from
a velocity-time
graph?
 You can determine the acceleration by finding
the slope of the line.
 Slope = Rise (y2 – y1)
Run (x2 – x1)
 The acceleration of the car in the
graph can be calculated by finding
two points on the line and finding
the slope.
Example:
Point 1: (1 s, 10 m/s)
Point 2: (4 s, 0 m/s)
Slope = 0 – 10 = - 3.3 m/s2
4–1
OBJECTIVE 2:
(Continued)
Determine speed from a distance-time graph.
Determine acceleration from a velocity-time graph.
What is the speed of the flying eagle in the
graph to the left?
A. 50
50 m/s
m/s
B. 15 m/s
C. 500 m/s
D. 5 m/s
OBJECTIVE 3:
Recognize that all objects have momentum.
State and apply the Law of Conservation of Momentum.
What is momentum?

Momentum is a quantity that is defined as the
product of an object’s mass and it’s velocity.
What does the
momentum of an
object rely on?

The momentum of an object depends on both its
velocity and its mass.
A heavier object will have a greater momentum.
An object that is moving faster will have a greater
momentum.
Why do all objects have
momentum?

What does the Law of
Conservation of
Momentum say?

The total amount of momentum in a system is
conserved.
How can the Law of
Conservation of
Momentum be applied
to predict the motion of
two objects after a
collision?

If two objects collide with one another, the total
amount of momentum before the crash will equal
the total amount of momentum after the crash.
The momentum of the individual objects may
change, but when added together (total) they will be
equal.




All objects have momentum because all objects
have mass.
If the object is not moving, then its momentum is
equal to zero.
OBJECTIVE 3: Recognize that all objects have momentum.
(Continued)
State and apply the Law of Conservation of Momentum.
Which object has MORE momentum in each of
the following examples?
cartrain
and has
trainmore
with the
same
A. AThe
momentum.
velocity.
moving
ballball
andhas
a still
bat.momentum.
B. AThe
moving
more
C. Two
balls
Bothidentical
balls have
themoving
same with
momentum.
the
same speed in the same
direction.
balls
D. Two
Both identical
balls have
themoving
same at the
momentum,
the direction the
same speed but
in opposite
momentum
directions. is applied is opposite.
Because of the large mass
and high speed of this
bowling ball it has a lot of
momentum and is able to
knock over the pins easily.
If two objects with different masses and traveling
with different velocities collide, what law allows
you to predict the motion of the objects after the
collision?
A. Law of Conservation of Energy
B. Law of Conservation of Mass
Momentum
C. Law of Conservation of Momentum.
D. Newton’s Laws
OBJECTIVE 4:
Relate centripetal force, acceleration, and velocity to an
object moving in circular motion.
Explain why an object thrown or shot through the air
follows a curved path.
What is acceleration?

Acceleration is a change in velocity over time.
What is velocity?

Velocity is a quantity that relates how fast an object
is moving as well as what direction the object is
moving in.
What is centripetal
force?

Centripetal force is the force that pulls an object
inward when that object is spinning rapidly around a
center.
When you drive around a corner in the road at high
speeds, the reason you tend to lean in the direction
you are turning is because of the centripetal force.

How do acceleration,
velocity, and centripetal
force all relate to
circular motion?



What are the two
factors that cause
thrown objects to follow
a curved path?


As an object moves in a circular pattern, its velocity
is constantly changing because it is changing
direction.
Since acceleration is a change in velocity, as the
object moves in a circle and its velocity changes so
will its acceleration.
The centripetal force is the force that keeps an
object moving in a circle from flying outward due to
its acceleration.
Gravity.
Air resistance.
OBJECTIVE 4: Relate centripetal force, acceleration, and velocity to an
(Continued)
object moving in circular motion.
Explain why an object thrown or shot through the air
follows a curved path.
Why would a cannonball shot into the air follow
a curved path?
A. Gravity
Gravity and
and air
air resistance
resistance will
will cause
cause
the cannonball to slow
B. The rotation of the Earth
C. The lack of gunpowder would cause
the cannonball back to the Earth
D. None of the above.
When an object moves in a circular path, it
accelerates toward the center of the circle as a
result of _______________.
A. terminal velocity.
B. momentum.
C. centripetal force.
D. frictional force.
OBJECTIVE 5: Describe how the push or pull of a force affects the
motion of an object.
What is force?

Force is the cause of acceleration or a change in an
object’s velocity.
What are balanced
forces?

Balanced forces are forces acting on an object that
combine to produce a net acceleration equal to
zero.
What are unbalanced
forces?

Unbalanced forces are forces acting on an object
that combine to produce a net acceleration that is
NOT equal to zero.
Unbalanced forces cause a change in an object’s
velocity.

How can we relate
balanced and
unbalanced forces to a
real life situation?



In a tug-of-war each side exerts a force on the rope.
If the opposing forces are equal, they are balanced,
and the rope does not move.
If one force is greater than the other, the forces are
unbalanced, and the rope moves in the direction of
the greater force.
OBJECTIVE 5: Describe how the push or pull of a force affects the
motion of an object.
There are 20 students preparing to engage in a
tug-of-war. The 10 biggest students get on one
team and the 10 smallest students get on the
other team. What will cause the smaller team to
be dragged into the mud?
A. Secret forces.
B. Balanced forces.
C. Unbalanced forces.
D. No forces.
Which of the following situations represents
balanced forces (there is no change in
velocity)?
A. A car turns right without slowing
down.
B. A spacecraft moves in one direction
at a constant speed.
C. A cyclist coasts downhill, going
faster and faster.
D. A tennis racket hits a tennis ball.
OBJECTIVE 6: Relate net force to the velocity of an object.
Give examples of situations involving balanced and
unbalanced forces.
What is net force?
 Net force is the combination of all the forces
acting on an object at any given time.
How does the net
force on an object
affect its velocity?
 If the net force on an object is greater than
What are some
examples of
situations involving
balanced forces?
 A bicycle standing against a tree.
 A car going down a straight road at a constant
What are some
examples of
situations involving
unbalanced forces?
 A truck driving around a curve in the
zero, than the object’s velocity will change.
 If the forces on an object are balanced there
will be no change in the object’s velocity –
speed or direction.
speed of 60 miles/hour.
mountains.
 A bike falling over from upright to lying on the
ground.
OBJECTIVE 6: Relate net force to the velocity of an object.
(Continued)
Give examples of situations involving balanced and
unbalanced forces.
When the velocity of an object changes,
it has been acted upon by a(n)
_____________.
A.
A. force.
force.
B. momentum.
C. inertia.
D. deceleration.
If the net force on an object is zero, then the
object has ____________.
A. reaction forces.
B. action forces.
C. balanced forces.
D. unbalanced forces.
OBJECTIVE 6: Relate net force to the velocity of an object.
(Continued)
Give examples of situations involving balanced and
unbalanced forces.
If an object has a net force acting on it, it will accelerate. The object
will speed up, slow down or change direction. An unbalanced force (net
force) acting on an object changes its speed and/or direction of motion.
An unbalanced force is an unopposed force that causes a change in
motion. A net force = unbalanced force. If however, the forces are
balanced (in equilibrium) and there is no net force, the object will
not accelerate and the velocity will remain constant.
 A rocket applies an additional force of 10
Newtons to the 10 Newtons that are applied
by the wheels. What is the net force if the
parachute continues to apply 7 Newtons in
the other direction?
 The net force would equal 13 Newtons,
forward. The mass will accelerate.
OBJECTIVE 7: Explain how friction affects an object’s motion.
Relate the type of surface to the amount of friction
produced.
What is friction?
 Friction is the force between two objects in
contact that opposes or slows down the
motion of either object.
What else does
friction affect?
 Friction can also affect objects that are not
moving.
 For example, a truck parked on a hill does not
move because the force of friction between
the brakes and the wheels balances the force
of gravity.
What does the
type of surface
have to do with the
amount of friction
produced?
 The rougher the surface is the more friction
it will produce.
 For example, a gravel road would produce a
lot more friction than an ice rink.
OBJECTIVE 7: Explain how friction affects an object’s motion.
(Continued)
Relate the type of surface to the amount of friction
produced.
Which of the following situations will produce
more friction?
A. Car sliding on the ice.
B. Car sliding on an unfrozen highway.
C. Car sliding on grass.
D. All of these situations have the same
amount of friction.
An object sliding across a frozen pond will
eventually come to a stop. The reason the
motion will stop is because of the contact
between the object and the ice. This force
between objects in motion is called _______.
A. a Newton.
B. friction.
C. a balanced force.
D. gravity.
OBJECTIVE 8:
State Newton’s three laws of motion and apply each of them to
everyday situations.
Use Newton’s first law to evaluate the effect of using safety
devices in automobiles including seatbelts and air bags.
What is Newton’s first
law of motion?

An object at rest tends to stay at rest and an object
in motion stays in motion at the same velocity
unless acted upon by an unbalanced force.
What is Newton’s
second law of
motion?

Force = mass x acceleration
What is Newton’s third
law of motion?

For every action there is an equal and opposite
reaction.
How can we apply
Newton’s first law of
motion to the use of
safety devices in the
car?

During an abrupt stop, people in a car, including
children in car seats would continue to move
forward until they are acted upon by a force that
stops them – like the windshield.

Car seats, seatbelts, air bags and other car safety
devices act as that outside force, stopping a person
or child before they are injured by hitting the
windshield or dashboard of a car.
OBJECTIVE 8:
(Continued)
State Newton’s three laws of motion and apply each of them to
everyday situations.
Use Newton’s first law to evaluate the effect of using safety
devices in automobiles including seatbelts and air bags.
Name which of Newton’s three laws apply to the
following situations:
A. You feel a force against the sole of your
foot as you take a step forward.
 Newton’s third law
B. A meteor moving in a straight path
changes direction when it flies by the
Earth.
 Newton’s first law
Newton’s third law says
that as gases push this
rocket forward the rocket
pushes gases backward.
C. A full grocery cart that is pushed starts
moving and increase speed, but the
same push makes an empty cart go
faster.
 Newton’s second law
D. A skateboarder changes direction after
a collision with a bicyclist.
 Newton’s first law.
OBJECTIVE 9:
Use Newton’s second law to calculate force, mass, and
acceleration.
Explain how the force acting on an object is related to the
object’s mass and acceleration.
What is Newton’s
Second Law?

Force = Mass x Acceleration or F = m x a
What is an example of
Newton’s second law?

If you push an empty shopping cart and a full
shopping cart across the parking lot with the same
amount of force, the empty cart will accelerate faster
because it has less mass.
How do I use Newton’s
second law to solve
problems involving
force, mass, and
acceleration?
Problem: A soccer ball is kicked with a force of 15.2 N.
The soccer ball has a mass of 2.45 kg. What is the
ball’s acceleration?
Knowns: F = 15.2 N
m = 2.45 kg
a = F/m
15.2 N
2.45 kg
a
Unknown: a = ? m/s2
15.2 / 2.45 = 6.3 m/s2
Use Newton’s second law to calculate force, mass, and
acceleration.
OBJECTIVE 9:
(Continued)
Explain how the force acting on an object is related to the
object’s mass and acceleration.
Which of Newton’s Laws of Motion deals with
the amount of force used to push a stalled car
so it will accelerate at 25 m/s2?
A. Newton’s First Law of Motion.
B. Newton’s Second Law of Motion.
C. Newton’s Third Law of Motion.
D. None of the above.
If a 35 kg mass is accelerated at 15 m/s2,
what force is being applied to the object?
A. 2.3 N
B. 530 N
C. 0.14 N
D. None of the above.
Remember:
F
m
a
OBJECTIVE 10:
What is mass?
Differentiate between mass and
weight.
 Mass is how much matter is in an object.
 Measured in grams, kilograms, pounds,
etc.
 When you weigh something, you are
actually finding that objects mass.
 Mass does not change unless you
remove some of the matter in the object.
What is weight?
 Weight is a force.
 Since force is mass X acceleration,
weight is the mass of an object X gravity
 Your mass doesn’t change, but your
weight will decrease on the moon
because there is less gravity.
OBJECTIVE 10:
(Continued)
Differentiate between mass and
weight.
If you are told an object is 50 kilograms, is this
the mass or weight of the object?
A. Mass
B. Weight
If you are told to measure the force an object
is exerting on a table, you would be
finding what?
A. Mass
B. Weight
OBJECTIVE 11:
Determine when work is being done on an object.
Describe the relationship between power, work and time.
Calculate the work done on an object and the rate at which
work is done.

What is work?

Work on an object is done when a force is applied to
that object and it moves in the direction of the force.
In order for work to be done, THE OBJECT HAS TO
MOVE. If you are just holding a book above your
head, work is not being done. If you are LIFTING
that book above your head, you are doing work.
How do you calculate
work?

What is an example of
solving a problem
involving work, force,
and distance?
Problem: Pulling a boat forward into a docking slip
requires 157 J of work. The boat must be pulled a
total distance of 5.3 m. What is the force with which
the boat is pulled?
Work = Force x Distance or W = F x d
Knowns: W = 157 J
d = 5.3 m
157 J
F
5.3 m
F=W/d
Unknown: F = ? N
157 / 5.3 = 29.6 N
OBJECTIVE 11:
(Continued)
Determine when work is being done on an object.
Describe the relationship between power, work and time.
Calculate the work done on an object and the rate at which
work is done.
What is power?

Power is a measure of how fast work is getting
done.
How do you calculate
power?

Power = Work
Time
What is an example of
solving a problem
involving power, work
and time?
Problem: An electric mixer uses 350 W. If 8750 J of
work are done by the mixer; how long has the mixer
run?
Knowns: P = 350 W
W = 8750 J
t=W/P
8750 J
350 W
t
or
P=W
t
Unknown: t = ? s
8750 / 350 = 25 s
OBJECTIVE 11:
(Continued)
Determine when work is being done on an object.
Describe the relationship between power, work and time.
Calculate the work done on an object and the rate at which
work is done.
Remember:
W
F
d
If you pull a wagon (weight of 20N) for 20 m
and it takes 5.0 s, calcualte the power
needed.
Remember:
W
P
In the scientific world, you are doing work
when you are doing which of the following
activities?
A. You hold a box over your head.
B. You sit and watch a baby sleep.
You lift
lift aa box
box of
of books
books over
over your
your
C. You
head.
head.
t
A.
B.
C.
D.
100 W
0.25 W
4W
40 W
OBJECTIVE 12: Name and describe the six types of simple machines.
Recognize simple machines within compound machines.
What are the six types of
simple machines?

Simple lever, pulley, wheel & axle, simple inclined plane,
wedge, and screw
What is a simple lever?

A lever has a rigid arm that turns around a point called the
fulcrum.
What is a pulley?

A pulley is a first class lever in which the rope is considered
the rigid arm and the point in the middle of the pulley is the
fulcrum.
What is a wheel & axle?

A wheel & axle is a lever or pulley connected to a shaft.
What is an inclined plane?

An inclined plane is a ramp that multiplies and redirects the
force required to move something.
What is a wedge?

A wedge is a modified inclined plane in which a single
downward force is split into two lateral forces.
What is a screw?

A screw is an inclined plane wrapped around a cylinder.
What is a compound
machine?

A compound machine contains more than one simple
machine.
What is an example of a
compound machine?


A bicycle.
A bicycle contains a wheel & axle, a lever, and several
screws.
OBJECTIVE 12: Name and describe the six types of simple machines.
Recognize simple machines within compound machines.
Name the simple machines used in a situation
where a wheelchair is used to take a person
up a ramp.
A. Wheel & axle, wedge, and pulley
B. Wheel & axle and inclined plane
C. Simple lever, screw, and pulley
D. Wedge, screw, and pulley
What simple machines can be found in a can
opener?
A. Wedge, inclined plane, pulleys and
wheel & axle
B. Screws, wedge, lever and wheel &
axle
C. Lever, screws, gears, and wheels
D. Wheel & axle, levers, screws and
pulleys
OBJECTIVE 13:
Discuss and calculate the mechanical advantage of various
machines.
Investigate how changing force or distance affects the
mechanical advantage of a simple machine.
What is mechanical  Mechanical advantage is a quantity that
advantage?
measures how much a machine multiples the
force or distance.
How do different
machines affect
mechanical
advantage?
 Machines can change the direction of an input
force or increase an output force by changing the
distance over which a force is applied
 A car jack and a wheelchair ramp are examples
of machines that make work easier by increasing
the distance over which the force is applied.
How do you calculate
mechanical
 Increasing the distance means less force is
advantage?
required to do the work.
 Mechanical Advantage = Output Force/
Input Force
 For inclined planes: MA = Length/Height
OBJECTIVE 13:
(Continued)
Discuss and calculate the mechanical advantage of various
machines.
Investigate how changing force or distance affects the
mechanical advantage of a simple machine.
Calculate the mechanical advantage of a
ramp that has a length of 5.0 m and a height
of 2.5 m.
A. 2.0 m
B. 0.5 m
C. 12.5 m
D. 0.08 m
If you increase the length of a ramp (increase
the input distance), what does this do to the
force you need to push an object up the
ramp?
A. It multiplies the force required to
push the object.
B. It makes it harder to push the object.
C. It makes it easier to push the object.
D. Both A and C.
OBJECTIVE 14:
Analyze the efficiency of machines.
What is
efficiency?
 It is a percentage that measures the ratio
How do you
calculate the
efficiency of a
machine?
 Efficiency = Useful Work Output X 100
Can a machine
have 100%
efficiency?
 No, because in all machines there is
of useful work output to work input.
Work Input
 Hint: If you have trouble deciding which
number is the work output, place the
smallest number on top
some work or energy that is lost due to
friction.
 The energy is lost in the form of heat.
OBJECTIVE 14:
(Continue)
Analyze the efficiency of machines.
A pulley system raises a 39 N log with an applied
force fo 45 N. What is the efficiency?
A. 1755 %
87 %
B. 87%
C. 11%
D. 50 %
Like all machines, the
pulleys on a sailboat are
less that 100% efficient.
Which of the following explains why simple
machines never operate at 100% efficiency?
A.
A. Gains
Gains in
in mechanical
mechanical advantage
advantage are
are
always
always accompanied
accompanied by
by energy
energy
losses
–
mainly
in
the
form
losses – mainly in the form of
of heat.
heat.
B. Machines are continually improving,
but they still suffer from design flaws.
C. Friction adds nearly as much work as
simple machines subtract.
D. The added weight of simple machines
subtracts from the mechanical
advantage.
OBJECTIVE 15: Explain the difference between potential and
kinetic energy.
What is potential
energy?
 The stored energy resulting from the
What is kinetic
energy?
 The energy of a moving object.
 The faster the object is moving the more
relative positions of objects in a system.
 It depends on the height of the object;
the higher the object, the more potential
energy it has.
kinetic energy it has.
What are some
examples of
potential energy?
 A stretched rubber band.
 An apple hanging in a tree
OBJECTIVE 15: Explain the difference between potential and
(Continued)
kinetic energy.
At what point on a roller coaster, is the
potential energy the highest?
A. At the top of the highest hill.
B. At the bottom of the highest hill.
C. On the way down the highest hill.
D. None of the above.
For any object to have kinetic energy it must
meet which of the following requirements?
A. It must be high in the air.
B. It must be near the ground.
C. It must be under water.
D. It must be in motion.
Objective 16:
Apply the Law of Conservation of Energy to a
mechanical system such as a pendulum.
What is the Law of
Conservation of
Energy?
 Energy cannot be created or destroyed; it can
What is mechanical
energy?
 The sum of the kinetic and potential energy in
How does this apply
to a mechanical
system?
 In a mechanical system, the total kinetic and
What are some
examples of
mechanical
systems?
 A roller coaster
 A pendulum
only change form.
a system.
potential energy will always be the same.
 The energy may change from potential to
kinetic energy, but the total will not change.
 Energy can be lost as heat due to friction.
Objective 16:
(Continued)
Apply the Law of Conservation of Energy to a
mechanical system such as a pendulum.
If you let a pendulum swing long enough
it will start to slow down and eventually
stop. That suggests that the system has
lost energy. What happens to this lost
energy?
A. Gravity is decreased.
B. Energy is destroyed.
C. Some energy is lost due to
friction.
friction.
D. Energy is created.
Objective 17:
Identify and describe transformations of energy.
How can we store
energy?


What are some of the
transformations of
energy that can occur?
and
What are examples of
these transformations?




Energy input into a system as the initial work done
on that system can be stored as gravitational
potential energy.
For example, on a roller coaster, the conveyor belt
at the beginning of the ride is doing work and storing
that energy as gravitational potential energy.
Potential energy can become kinetic energy.
On a roller coaster all of the energy of the cars is
potential energy at the top of a tall hill; as the car
accelerates down the hill, the potential energy is
transformed to kinetic energy.
Kinetic energy can be transformed back into
potential energy.
At the lowest point of the roller coaster the car has
NO potential enregy. Kinetic energy gets converted
back into potential energy as the car is lifted up
another hill.
Objective 17:
(Continued)
Identify and describe transformations of energy.
Which of the following situations does
not involve potential energy being
changed into kinetic energy?
A. An apple falling from a tree..
B. Shooting a dart from a springloaded gun.
C. Pulling back on the string of a
bow.
D. A creek flowing down hill.
Objective 18:
Define temperature in terms of the average kinetic energy of atoms or
molecules.
Contrast heat and temperature.
Describe heat as a form of energy transfer.
What is kinetic
energy?
 The energy of motion.
What is heat?
 Heat is the transfer of energy from the
particles of one object to those of another
object due to a temperature difference
between the two objects.
 Heat flows as energy from an object with a
higher temperature to and object with a lower
temperature.
 For example, if I put an ice cube on my hand,
the reason that ice cube melts is because heat
from my hand (warmer) is transferring to the
ice (cooler).
What is
temperature?
 Temperature is the measure of the amount of
kinetic energy in an object.
Objective 18: Define temperature in terms of the average kinetic
energy of atoms or (Continued) molecules.
Contrast heat and temperature.
Describe heat as a form of energy transfer.
Determine which of the following are
examples of heat ?
A. A nurse checks your temperature
which is 98.6 F and rising.
B. You check the outside to see what to
wear.
C.
C. A
A hot
hot water
water bottle
bottle transfers
transfers energy
energy
from
fromthe
thehot
hotwater
watertotoyour
yourskin.
skin.
D. The temperature of a roasting turkey.
As the kinetic energy of the molecule in a
substance increases ________________.
A.
A. the
the temperature
temperature of
of the
the substance
substance
increases.
increases.
B. the temperature of the substance
decreases.
C. potential energy of the substance
changes.
D. temperature remains the same.
Objective 19:
Investigate and demonstrate how energy is transferred by
conduction, convection, and radiation.
What is conduction?
What is an example of
conduction?



What is radiation?


What is an example of
radiation?
Conduction is the transfer of energy as heat between
particles as they collide within a substance or between two
objects in contact.
In order for conduction to occur, there MUST BE
CONTACT either between two objects or between
molecules within an object.
Radiation is the the transfer of energy by electromagnetic
waves.
Radiation DOES NOT involve the movement of matter.
You feel warm when you stand in sunlight because of
radiation.
Objective 19:
transferred by
Investigate and demonstrate how energy is
conduction, convection, and radiation.
 A metal rod may becomes hot when
What is
convection?
held in your hand near a flame due to
convection.
 Convection is the transfer of energy
Which picture
respresents an
example of
convection?
by the movement of fluids with different
temperatures.
 It is based on the principle that warm
gases or liquids rise and cool gases or
liquids sink (or descend).
 Pasta boiling on the stove rolls in the
water due to convection.
 The Active Solar heating system in a
house.
Objective 19:
(Continued)
Investigate and demonstrate how energy is transferred
by conduction, convection, and radiation.
Why does convection occur?
A. A nurse checks your temperature
which is 98.6 F and rising.
B. You check the outside to see what to
wear.
C. AAhot
hotwater
waterbottle
bottletransfers
transfersenergy
energy
C.
from the hot water to your skin.
D. The temperature of a roasting turkey.
As the kinetic energy of the molecule in a
substance increases ________________.
A.
A. the
the temperature
temperature of
of the
the substance
substance
increases.
increases.
B. the temperature of the substance
decreases.
C. potential energy of the substance
changes.
D. temperature remains the same.
Objective 20:
Classify materials as conductors or insulators for heat.
Distinguish between conductors, superconductors,
semiconductors and insulators.
What is the difference
between a conductor
and an insulator?

What is the difference
between a conductor
and a superconductor?





What is the difference
between a conductor
and a semi-conductor?


A conductor is a material through which energy in the
form of heat or electricity can flow easily.
An insulator is a material that DOES NOT allow energy
in the form of heat and electricity to move through it
easily.
A conductor, even though it does conduct electricity
well, still has some resistance that slows the current
down.
Some metals, such as tin and mercury, have ZERO
resistance when their temperature is decreased below a
certain temperature.
These metals under the right conditions (temperature)
are considered superconductors (ZERO resistance).
Superconductors are used in powerful magnets and in
high speed, super-trains.
Semi-conductors are in between a conductor and an
insulator.
Silicon, used in computer chips, is a common semiconductor.
Objective 20:
(Continued)
Classify materials as conductors or insulators for heat.
Distinguish between conductors, superconductors,
semiconductors and insulators.
Which of the following would work best in
magnetic levitation seen in the super-trains
that move on monorails?
A. Conductors.
B. Semi-conductors.
Superconductors.
C. Superconductors
D. Insulators.
A metal spoon gets hot when you let it sit in
boiling water. A wooden spoon will still be
cool to the touch. The metal spoon and
wooden spoon are examples of what?
A. An insulator and a conductor.
B. A semi-conductor and an insulator.
C. A conductor and an insulator.
D. A superconductor and a conductor.
Objective 21: Recognize that waves transfer energy.
Explain the relationship between particle vibration and wave
motion.
What is a wave?



A wave is a disturbance that transmits energy
through matter or space.
Waves can do work on objects.
The larger the wave, the more energy it contains.
What are some
examples of how
waves transfer energy?



Water waves carry a surfer toward the shore.
Water waves erode the sand off the beach.
Sound waves do work on your eardrum causing it to
vibrate.
In a transverse wave,
in which direction do the
particles of the medium
vibrate?

In a transverse wave, the particles of the medium
vibrate perpendicular to the wave motion.
For example, in water waves, if the wave is
moving side-to-side, the medium would be moving
both up and down.
In a longitudinal wave,
in which direction do the
particles of the medium
vibrate?



In a longitudinal wave, the particles of the medium
vibrate parallel to the wave motion.
For example, in a slinky, if the wave is moving sideto-side, the medium would also be moving side-toside.
Objective 21:
(Continued)
Recognize that waves transfer energy.
Explain the relationship between particle vibration and wave
motion.
Most waves are caused by _________.
A. velocity.
B. amplitude.
C.
C. aa vibration.
vibration.
D. earthquakes.
For which type of waves do particles in the
medium vibrate perpendicularly to the
direction in which the waves are traveling?
A.
A. Transverse
Transverse waves.
waves.
B. Longitudinal waves
C. P waves
D. None of the above.
Objective 22: Identify and demonstrate transverse, longitudinal, and standing
waves.
Label the crest, trough, amplitude, and wavelength of a wave.
What does a
transverse wave look
like?
How would you label
wavelength, trough,
crest, and amplitude?
What does a
longitudinal wave look
like?
How can you identify
the wavelength on a
longitudinal wave?
Objective 22: Identify and demonstrate transverse, longitudinal, and standing
(Continued) waves.
Label the crest, trough, amplitude, and wavelength of a wave.
What is a
standing wave?
What does a
standing wave
look like?
 A standing wave is one that contains one
or more nodes, as with the wave lab we
did earlier in the year.
 They are caused by having a barrier to
reflect off of and then the reflected wave
positively interferes with the original wave
to increase the waves amplitude between
the nodes.
Objective 22:
(Continued)
Identify and demonstrate transverse, longitudinal, and standing
waves.
Label the crest, trough, amplitude, and wavelength of a wave.
The wave pictured above is a _________.
A. longitudinal wave.
B. transverse
transverse wave.
wave.
C. standing wave.
D. surfer wave.
What is he part of the wave labeled A?
A. Crest.
B. Trough.
C. Wavelength.
C.
D. Amplitude.
Objective 23:
Distinguish between S waves, P waves and surface waves in
earthquakes.
Explain how seismic waves affect the movement of the
earth’s lithosphere.
What happens to the
earth’s lithosphere during
an earthquake?



What is a seismic wave?



Earthquakes occur between boundaries between tectonic
plates.
When the plates move along one another, an earthquake
starts.
Different waves are created at the center of the earthquake
and move outward.
Energy from earthquakes is transferred through earth by
seismic waves.
There are three types of seismic waves: P waves, S waves,
and surface waves.
Both P waves and S waves move outward from the center of
the earthquake.
What is a P wave?


P waves are longitudinal waves.
They are the fastest type of seismic waves and they move
through the earth first.
What is an S wave?


S waves are transverse waves.
They are slower than P waves.
What are surface waves?



Surface waves move along the surface of the earth.
They are the slowest moving of all seismic waves.
These waves cause the most destruction during an
earthquake.
Objective 23:
(Continued)
Distinguish between S waves, P waves and surface
waves in earthquakes.
Explain how seismic waves affect the movement of the
earth’s lithosphere.
The boundaries between tectonic plates grind
against each other producing earthquakes
and releasing energy in the form of ____.
A. heat waves.
B. P waves.
C. S waves.
D. seismic waves.
The fastest moving of the waves generated by
an earthquake are the _____.
A. S waves.
B. P waves.
B.
C. surface waves.
D. seismic waves.
OBJECTIVE 24: Determine the frequency and period of a wave.
Solve problems involving wave speed, frequency, and wavelength.
Describe the Doppler Effect.
What is frequency?


Frequency is how many waves pass a given point
in 1 second.
The units for frequency are Hertz (Hz)

Period is the amount of time, in seconds (s), that it
takes for one wave to pass a given point.
How are frequency and
period related?


They are reciprocals of each other.
Frequency =
1
Period =
1
Period
Frequency
What is an example of
a problem involving the
period and frequency of
a wave?
Problem: A person is floating in the ocean in an inner
tube. A wave passes the inner tube every 2
seconds. What is the period of the waves? What is
the frequency?
What is period?
Knowns: Period = 2 s
Frequency =
Unknowns: f = ? Hz
1
= 1
Period
2
=
0.5 Hz
OBJECTIVE 24: Determine the frequency and period of a wave.
(Continued)
Solve problems involving wave speed, frequency, and wavelength.
Describe the Doppler Effect.
What is wave speed?


How do you calculate
wave speed?

Wave speed is the speed at which a wave passes
through a medium.
It is a rate.
Wave speed = frequency X wavelength
or
v=f xλ
What is an example of
a problem involving
wave speed, frequency
and wavelength?
Problem: The speed of sound in air is about 340 m/s.
What is the wavelength of a sound wave with a
frequency of 220 Hz?
Knowns: f = 220 Hz
v = 240 m/s
λ=v/f
240 m/s
220 Hz
λ
Unknown: λ = ? m
240 / 220 = 1.5 m
OBJECTIVE 24:
(Continued)
Determine the frequency and period of a wave.
Solve problems involving wave speed, frequency, and wavelength.
Describe the Doppler Effect.
What is the doppler
effect?
 Imagine that you are standing on a corner as
an ambulance rushes by .As the ambulance
passes, the sound of the siren changes from a
high pitch to a low pitch. Why?
 The Doppler effect is an observed change in
the frequency of wave when the source or
observer is moving.
Suppose a train is approaching you as you stand on the loading platform at the
railway station. As the train approaches, it slows down. All the while, the
engineer is sounding the horn at a constant frequency of 500 Hz. Which of the
following statements would best describe the pitch and changes in pitch that you
hear?
The pitch is greater than 500 Hz as the train approaches, and
then decreases to 500 Hz as the train comes to a stop.
OBJECTIVE 24: Determine the frequency and period of a wave.
(Continued)
Solve problems involving wave speed, frequency, and wavelength.
Describe the Doppler Effect.
Ocean waves are hitting a beach at a rate of
2.0 Hz. The distance between wave crests is
12 m. Calculate the speed of the waves.
A. 0.17 m/s
B. 6.0 m/s
C. 24 m/s
D. 1 m/s
As the airplane moves closer to
your ear the sound waves
produced by the plane are
closer together, so you hear a
higher pitched sound.
The number of waves passing a given point
each second is called the __________?
A. frequency.
B. wave speed.
C. wavelength.
D. amplitude. Remember:
v
f
λ
Objective 25: Explain how resonance affects sound.
What is a natural
frequency?
 All objects have a set of natural frequencies.
 If objects are allowed to vibrate at their natural
frequencies, they will generate a very large
amplitude vibration.
What is resonance?
 Resonance is an effect in which the vibrations
of one object causes another object to vibrate
at its natural frequency.
How does
resonance amplify
sound?
 Sound is amplified because both the object
generating the sound and the object that
resonates are both vibrating at the same
frequency.
 Example: An acoustic guitar resonates with
the guitar strings allowing it to be played
without an amplifier.
Objective 25:
(Continued)
Explain how resonance affects sound.
Resonance refers to an effect in which
_________.
A. one object causes another object to
vibrate at natural frequencies.
B. Intensity of sound decreases over
time.
C. pitch of a note is compared to a pure
tone.
D. vibration of a string or column of air
causes an object to vibrate at its
natural frequencies.
Why does an acoustic guitar not need an
amplifier?
A. The guitar interferes with the
vibrations of the strings.
B. The strings don’t vibrate.
C. The guitar resonates with the strings
amplifying
amplifying the
the sound.
sound.
D. All of the above.
Objective 26:
Distinguish between constructive and destructive
interference.
What is
interference?
 When two waves arrive at the same place
What is
constructive
interference?
 Any interference in which waves combine
What is
destructive
interference?
 Any interference in which waves combine
at the same time.
so that the resulting wave is bigger than
the original.
so that the resulting wave is smaller than
the largest of the original waves.
Objective 26:
(Continued)
Distinguish between constructive and destructive
interference.
Which of the following statements is true about wave interference?
A. Wave interference occurs with transverse waves but not longitudinal
waves.
B. Constructive interference occurs when wave frequencies overlap.
C. Destructive interference underlies the destruction wrought by rogue
waves.
D. Constructive interference adds the wave height of one wave crest to
the wave height of an overlapping wave crest
crest.
Objective 27: Identify and demonstrate examples of reflection, refraction, and diffraction in waves.
Describe how light reflects off smooth and rough surfaces.
Explain the law of reflection.
Illustrate how light is refracted as it passes between mediums.
Describe how prisms disperse light and how rainbows form.
Explain how fiber optics use total internal reflection.
What is reflection?

The bouncing back of a wave as it hits a surface or boundary.
What is the law of
reflection?

The angle of the light as it hits the boundary is equal to the
angle of the light as it is reflected off the boundary.
When light reflects off of a
rough surface, what
happens?

Light rays reflected from a rough surface are reflected in many
different directions.
The reflection of light into random directions is called diffuse
reflection.
What is refraction?

The bending of waves as they
pass from one medium to another.
How does the refraction of
light differ when it passes
between different
mediums?

When light moves from a material in which its speed is higher
(air) to a material in which its speed is lower (water), the ray is
bent toward the normal.
When light moves from a material in which its speed is lower
(water) to a material in which its speed is higher (air), the ray
is bent away from the normal.


Objective 27: Identify and demonstrate examples of reflection, refraction, and diffraction in waves.
(Continued) Describe how light reflects off smooth and rough surfaces.
Explain the law of reflection.
Illustrate how light is refracted as it passes between mediums.
Describe how prisms disperse light and how rainbows form.
Explain how fiber optics use total internal reflection.
What is diffraction?

The bending of a wave as it passes an edge or an opening.
What does diffraction look
like?

Diffraction patterns look different depending on the type of
light being diffracted and the edge or opening it is being
diffracted through.
Below is an example of diffraction of a red laser light beam
through a diffraction grating.

What is dispersion?


An effect in which white light separates into its component
colors.
The colors of light that are focused through a prism are
separated by their wave speed.
Objective 27: Identify and demonstrate examples of reflection, refraction, and diffraction in waves.
(Continued) Describe how light reflects off smooth and rough surfaces.
Explain the law of reflection.
Illustrate how light is refracted as it passes between mediums.
Describe how prisms disperse light and how rainbows form.
Explain how fiber optics use total internal reflection.
What is total internal
reflection?

If the angle at which light rays meet the boundary between two
mediums becomes large enough, the rays will be reflected as
if the boundary were a mirror. This type of reflection is called
total internal reflection.
Objective 27: Identify and demonstrate examples of reflection, refraction, and diffraction in waves.
(Continued) Describe how light reflects off smooth and rough surfaces.
Explain the law of reflection.
Illustrate how light is refracted as it passes between mediums.
Describe how prisms disperse light and how rainbows form.
Explain how fiber optics use total internal reflection.
How do fiber optics
use total internal
reflection?



How do rainbows form?

Light inside a fiber in a fiber-optic cable bounces off of
the walls of the fiber due to total internal reflection.
If the fibers are arranged in the same pattern at both
ends of the cable, the light that enters one end can
produce a clear image at the other end.
They can be used to produce images of internal
organs during surgery as well as to transmit computer
images or signals for telephone calls.
Rainbows are formed due to a combination of
dispersion and total internal reflection
Objective 27: Identify and demonstrate examples of reflection, refraction, and diffraction in waves.
(Continued)
Describe how light reflects off smooth and rough surfaces.
Explain the law of reflection.
Illustrate how light is refracted as it passes between mediums.
Describe how prisms disperse light and how rainbows form.
Explain how fiber optics use total internal reflection.
When light rays reflect off a rough surface, they
_________.
A. scatter
scatter in
in many
many different
different directions.
directions.
A.
B. converge toward the normal.
C. diverge away from the normal.
D. decrease their speed and change
their angle.
Light that enters one end of a fiber optic cable
reaches the other end by means of ______.
A. dispersion.
B. magnification.
C. repeated intesification.
D. total internal reflection.
White light breaks up into different colors when it
passes through a prism because of _______.
A. differences
differences in
in wave
wave speed.
speed.
A.
B. total internal dispersion.
C. a combination of refraction and reflection.
D. droplets in the air.
Objective 28:
Explain how sonar and ultrasound imaging work.
Explain how electromagnetic waves are used in
communication, medicine, and technology, such as television,
radio, microwaves and optical fibers.
How does sonar work?


How do we use ultrasound
in sonograms and other
imaging technology?



How are different types of
light used in today’s
technology?





A sonar system determines distance by measuring the tim it
takes for sound waves to be reflected back from a surface.
A sonar device on a ship sends a pulse of sound downward,
and measures the time that it takes for the sound to be
reflected back from the ocean floor or other objects beneath
the ship. With that time, they can then find the distance.
At high frequencies, ultrasound waves can travel through
most materials. But some sound waves are reflected when
they pass from one type of material.
How much sound is reflected depends on the density of the
materials at each boundary.
These reflected sound waves from different boundary
surfaces are put together to form the image that appears on
a sonogram.
X-rays are used for imaging bones.
Gamma rays are used for radiation treatment of cancer
patients.
Infrared light is used for CAT scans and MRI technology.
Microwaves are used for cooking.
Radio waves are used in communications and in radar
technology.
Objective 28: Explain how sonar and ultrasound imaging work.
(Continued)
Explain how electromagnetic waves are used in
communication, medicine, and technology, such as television,
radio, microwaves and optical fibers.
How does sonar work?
A. Sonar measures the time it takes for
ultrasound waves to reflect from the object
back to the source of the sound.
B. Sonar measures the time it takes for
infrasound waves to reflect from the object
back to the source of the sound.
C. Sonar measures the time it takes for
ultrasound waves to be absorbed by an
object.
D. The object releases sound waves that
hit the source causing a vibration.
Ultrasound has come a long
way baby!
New 4D ultrasound technology
is giving us better and better
ways to view our bodies.
An ultrasound system can produce images of body
structures because sound waves _____.
A. travel only in a straight line.
B. travel at different speeds through materials of
different densities.
densities
C. cannot pass through liquids or gaseous
materials.
D. increase their speed and change their
direction as they leave the body.
Objective 29:
Show how mirrors form real and virtual images.
Distinguish between flat, convex, and concave mirrors and
give examples of their uses.
What is a virtual
image?

An image that forms at a point from which light rays
appear to come but do not actually come.
How does a mirror form
a virtual image?

When you stand in front of a mirror, your eyes
cannot tell where the light came from. Your eyes
think the light came from behind the mirror so the
image appears to come from behind the mirror.
What is a real image?

An image of an object formed by many light rays
coming together in a specific location, called a focal
point.
How does a mirror form
a real image?

A concave mirror will form a real image when the
light is reflected to a point in front of the mirror.
What is the difference
between a concave, a
convex and a flat
mirror?

Concave mirrors are indented and used in
telescopes and satellite dishes.
Convex mirrors bulge outward and are used in
many retail stores to get a wider view of the store
using one mirror.
Flat mirrors are just like those you have at home!


Objective 29: Show how mirrors form real and virtual images.
(Continued)
Distinguish between flat, convex, and concave mirrors and
give examples of their uses, such as in eyeglasses and
cameras.
Which type of mirror produces an image
resulting when light rays from an object are
focused onto a single point or small area in front
of the mirror?
A. Flat.
B. Convex
C. Concave
Concave
D. Centripital
Mirrors reflect images. One type of mirror
bulges out and distorts the image. One type of
mirror is curved inward and will make a real
image. One type of mirror makes a virtual
image. Choose the correct order or mirrors as
discussed above.
A. Flat, convex, and concave.
B. Concave, convex, and flat.
C. Flat, concave, and convex.
Convex, concave,
concave, and
and flat.
flat.
D. Convex,
Objective 30:
Relate the energy of light to the frequency of electromagnetic
waves.
Name and describe the regions of the electromagnetic
spectrum from the shortest to longest wavelength.
What happens to the
frequency of
electromagnetic waves
as the energy of the
light increases?

The energy of light increases as frequency
increases.
Radio waves: Yes, this is the same
kind of energy that radio stations
emit into the air for your radios to
capture and turn into your favorite
tunes. But radio waves are also
emitted by other things ... such as
stars and gases in space. You may
not be able to dance to what these
objects emit, but you can use it to
learn what they are made of.
Objective 30:
(Continued)
Relate the energy of light to the frequency of electromagnetic
waves.
Name and describe the regions of the electromagnetic
spectrum from the shortest to longest wavelength.
Microwaves: They will cook your popcorn in
just a few minutes! In space, microwaves
are used by astronomers to learn about the
structure of nearby galaxies, including our
own Milky Way!
Infrared: We often think of this as being the
same thing as 'heat', because it makes our
skin feel warm. In space, IR light maps the
dust between stars.
Visible: Yes, this is the part that our eyes
see. Visible radiation is emitted by
everything from fireflies to light bulbs to
stars ... also by fast-moving particles hitting
other particles.
Ultraviolet: We know that the Sun is a
source of ultraviolet (or UV) radiation,
because it is the UV rays that cause our
skin to burn! Stars and other "hot" objects in
space emit UV radiation.
Objective 30:
(Continued)
Relate the energy of light to the frequency of electromagnetic
waves.
Name and describe the regions of the electromagnetic
spectrum from the shortest to longest wavelength.
X-rays: your doctor uses them to look at
your bones and your dentist to look at your
teeth. Hot gases in the Universe also emit
X-rays .
Gamma-rays: radioactive materials (some
natural and others made by man in things
like nuclear power plants) can emit gammarays. Big particle accelerators that scientists
use to help them understand what matter is
made of can sometimes generate gammarays. But the biggest gamma-ray generator
of all is the Universe! It makes gamma
radiation in all kinds of ways.
Objective 30:
(Continued)
Relate the energy of light to the frequency of electromagnetic
waves.
Name and describe the regions of the electromagnetic
spectrum from the shortest to longest wavelength.
What type of wave has the lowest
frequency and the longest wavelength?
A. Radio waves.
B. Infrared waves.
C. Visible light.
D. X-rays
What type of electromagnetic wave is
used in radiation treatments for cancer
patients?
A. Radio waves.
B. Infrared waves.
C.
C. Gamma
Gammarays
rays
D. X-rays
OBJECTIVE 33: Describe how batteries are sources of voltage.
Compare the economic and environmental impacts of
using rechargeable or disposable batteries.
What is a cell?
 A device that is a source of electric current
because of a potential difference, or voltage,
between the terminals
What is a battery?
 Common batteries are electric cells
How does a battery
produce electricity?
 A voltage exists across the negative and
What are the
advantages and
disadvantages of
rechargeable
batteries?
 More expensive than disposable batteries
 Last only half as long as disposable batteries
 Environmentally sound – do not clutter up
positive terminals of a battery
 When the terminals are connected, a current
is produced by the flow of electrons from the
negative to positive terminal
landfills, no hazardous chemicals
 Can be recharged hundreds of times
 Retain a charge like disposable batteries
OBJECTIVE 33: Describe how batteries are sources of voltage.
(Continued)
Compare the economic and environmental impacts of
using rechargeable or disposable batteries.
Batteries typically have ________.
A. two positive terminals.
B. two negative terminals.
C.
one positive
positive and
and one
one negative
negative
C. one
terminal
terminal
D. no terminals.
Potential differences cause _________.
A. electrons to move from the positive
terminal to the negative terminal
B. electrons
electrons to
to move
move from
from the
the negative
negative
terminal to the positive terminal.
C. protons to move from the positive
terminal to the negative
terminal.
D. protons to move from the negative
terminal to the positive terminal.
OBJECTIVE 34: Use Ohm’s Law to calculate the resistance, current, or
voltage, given the other two quantities.
What is Ohm’s
Law?
 Current = Voltage
What units should be
used with this
equation?
 Resistance is in Ohms, Ω
 Voltage is in Volts, V
 Current is in Amps, A
Example of how to
use Ohm’s Law to
solve problems
involving resistance,
current, and voltage:
Problem: The current in a handheld video game
is 0.50 A. If the resistance of the game’s
circuitry is 12 Ω, what is the voltage produced
by the battery?
Resistance
Knowns: I = 0.50 A
R = 12 Ω
V
0.50 A 12 Ω
V=IxR
or I = V
R
Unknown: V = ? V
0.50 x 12 = 6 V
OBJECTIVE 34: Use Ohm’s Law to calculate the resistance, current, or
(Continued)
voltage, given the other two quantities.
A potential difference of 12 V produces a
current of 0.30 A in a piece of copper wire.
What is the resistance of the copper wire?
A. 12 Ω
B. 0.025 Ω
C. 40 Ω
Ω
D. 5 Ω
What is the voltage across a 75 Ω resistor
with 1.6 A of current?
A. 47 V
B. 120 V
C. 0.021 V
D. None of the above.
Remember:
V
I
R
OBJECTIVE 35: Distinguish between alternating and direct current.
What is current?


The rate that electric charges move through a conductor.
Current can be made up of positive, negative, or a
combination of both positive and negative charges.
What is direct current?

The charges always move from one terminal to the other in
the same direction.
Direct current always flows in the same direction along a
wire.

What is an example of a
source of direct current
(DC)?

A battery.
What is alternating
current?

An electric current that changes direction at regular
intervals.
Magnitude and direction of current depend on the
orientation of the loop in the magnetic field

What is an example of a
source of alternating
current (AC)?

Home electrical outlets.
OBJECTIVE 35: Distinguish between alternating and direct current.
(Continued)
A direct current ____________.
A. changes direction.
B. changes direction only when
converted.
C. only runs in one direction.
D. None of the above.
In an AC generator, the magnitude of the
current produced _____________.
A. depends on the orientation of the
loop within the magnetic field.
B. is minimum when the loop is
perpendicular to the magnetic field
C. varies with time.
D. All of the above.
OBJECTIVE 36:
Use schematic diagrams to represent a circuit.
Distinguish between series and parallel circuits.
Explain how fuses and circuit breakers are used to prevent
circuit overload.
OBJECTIVE 36:
(Continued)
Use schematic diagrams to represent a circuit.
Distinguish between series and parallel circuits.
Explain how fuses and circuit breakers are used to prevent
circuit overload.
What is a series circuit?




What is a parallel circuit?



Circuits that are connected in series
providing only one path that can
conduct electricity
The current in a series circuit is not
divided or split by multiple paths
If one element in a series circuit is
removed, the circuit will not work
Example: Christmas tree lights
Parallel circuits are connected
across common points providing
two or more paths for electricity to
be conducted
The current across each path is
determined by the amount of
resistance on that path
The greater the resistance  the
smaller the current on that path
OBJECTIVE 36:
(Continued)
Use schematic diagrams to represent a circuit.
Distinguish between series and parallel circuits.
Explain how fuses and circuit breakers are used to prevent
circuit overload.
How can a circuit
become overloaded?

When too many appliances are plugged into the
same outlet, the overall resistance of the circuit is
lowered causing more than a safe level of current to
flow through the wire. This causes an overload of
the circuit.
How can a fuse help?

Fuses stop the overloading of circuits by melting
and opening the circuit if too much current flows
through the circuit.
What is the difference
between a fuse and a
circuit breaker?

A circuit breaker does not melt when the circuit is
overloaded, instead it acts like a switch that simply
opens.
When a fuse “blows out” it must be replaced, but
when a circuit breaker opens it can be reset simply
by resetting the switch.
