Transcript Survival Needs… Food

2012 PVHS NHSPE Review
Science
Physics Part 1… Energy
What we need to know…
1. Which of the following examples has the
greatest thermal (internal) energy?
a) 5 kg of water with a temperature of
150°C
b) 8 kg of water with a temperature of
110°C
c) 10 kg of water with a temperature of
90°C
d) 100 kg of water with a temperature
of 28°C
2.
A ball is initially dropped from a height 4
meters. After the ball bounces it returns to a
height of only 2 meters. How much of the
ball’s initial gravitational potential energy was
transformed between the initial position and
the final position of the ball?
a) One fourth of the total energy.
b) Half of the total energy.
c) Double the total energy.
d) Four times the total energy.
3. Energy is created as the result which
activity?
a) Burning gasoline in an internal
combustion engine.
b) Damming a river for hydroelectric
power.
c) Rolling a marble down an incline plane.
d) Energy can only be transformed, not
created.
4.
Aluminum was once used as the wires in home construction.
Recently, it was changed to copper wires. Which of the
following statements BEST account for why aluminum was
replaced with copper?
a) When electrical energy is passed through a copper wire,
less of the energy removes copper atoms from the wire.
b) The electrical energy that a copper wire can transfer is
less than
an aluminum wire.
c) As a byproduct of transmission, more electrical energy is
transformed to wasted thermal energy in aluminum wire
than in copper
d) The electrical energy that passes through an aluminum
wire cannot be directed as well as the energy passing
through copper.
5. In an alternating current (AC) circuit,
a) voltages can be easily increased and decreased
within the circuit allowing for lower energy
losses during transmission.
b) voltages change direction several times a
second to generate electrical charge more
rapidly.
c) rapid current changes regulate the ease at
which electricity passes through the circuit.
d) current most often is high to prevent energy
losses during transmission, but can be low to
decrease the voltage in the circuit.
6. Which of the following describes how a dam
creates electricity?
a) Water is heated up and creates steam to turn
the generator to create electricity.
b) Gravitational potential energy transfers to
kinetic energy which turns a generator.
c) Electrons are removed from the water as it
passes and creates electricity.
d) Water flows over wires in the dam which
creates current from the water.
7. A hammer strikes a nail and drives the nail into
a block of wood. If the action force is the
hammer striking the nail, the reaction force is
a) the nail striking the wood with an equal and
opposite force.
b) the nail striking the hammer with an equal
and opposite force.
c) the wood striking the hammer with an equal
and opposite force.
d) the wood striking the nail with an equal and
opposite force.
8.Which of the following would
supply the greatest
acceleration when applied to a
10 kg mass?
a)5N
b)10N
c)15N
d)20N
9.
Use the diagram to answer the question below.
A cart is being pulled North across a
carpeted floor. Which direction is the
force of friction acting?
a)North
b)South
c) East
d)West
10.You have created a track out of cardboard for a
marble to travel down. In order for the marble to
complete the track, why does the first hill have to
be the highest?
a) The friction caused by the track resists the
motion of the marble.
b) The friction caused by the track increases the
motion of the marble.
c) Gravity is pulling down on the marble causing it
to slow down.
d) Gravity is pulling down on the marble causing it
to speed up.
What is Energy?
Energy is…
 The ability of an object to
produce a change in itself or
its environment
 It is a measure of the
capacity to produce change.
Sometimes Work is
associated with change
Work transfers energy, but
energy can also be
transferred by Heat and
Radiation
Can Energy be Created?
 Law of Conservation of Energy- Energy
cannot be created or destroyed
 Total amount of energy is constant
 Energy can only be stored or transferred
… stretching the bow transfers
chemical energy from your
muscles into potential energy in
the bow and string
… releasing the arrow transfers
potential energy in the bow to
kinetic energy in the arrow
Sun
Capacity
for change
Energy
light
waves
Can’t create
or destroy
Store it
radiation
Transfer it
 What is the earth’s primary
energy source?
The sun
does not
“burn” and
it does not
“create”
energy
 The sun releases the energy stored
in atoms through Fusion
 Fusion combines the atoms of an
element to create a different element
 Energy is transferred to earth by
Radiation
 Electromagnetic waves like light
 Higher frequency… higher energy
Energy
Can’t create
or destroy
Store it
Sun
Capacity
for change
Remember… Force is a pull
or push on an object andWaves
is
only related to Radiation
energy by
Transfer it
work…
energy is not a force
Work
 How else can energy transfer?
Light
Force
X
Distance
Friction
 Work transfers energy
 Work is a Force that causes displacement
(moves an object a distance)
 W=Fxd
 Whenever work is done there is Friction
 Friction always opposes motion and causes
energy loss to the environment
Energy
Sun
Capacity
for change
Light
Waves
Can’t create
or destroy
Radiation
Transfer it
 Store
How
else can energy
it
transfer?
 Heat also transfers
energy
 Heat is energy
transferred between
objects at different
temperatures

Higher temp… faster
atoms run into Lower
temp… slower atoms
 The random motion of
atoms is Thermal Energy
Force
Work
Heat
X
Distance
Friction
Thermal
Energy
Energy
Sun
Capacity
for change
Light
Waves
Can’t create
or destroy
Radiation
Transfer it
Store it
Force
Work
Heat
X
Distance
Friction
 Thermal Energy
 Virtually every energy transfer involves
friction and temperature differences
 Some energy is always lost to the
environment as thermal energy
 We try to counteract this by designing
more efficient devices
Thermal
Energy
Energy
Can’t create
or destroy
Store it
Capacity
 Howforischange
energy stored?
Sun
Light
 Kinetic energy is the energy stored in the
Waves
motion of objects
Radiationhas stored energy
 Any object in motion
Transfer it
Force
 KE = ½ mass x velocity2
 KE energy increasesWork
greatly with speed
X
Distance
Kinetic
Heat
Friction
Objects
in
motion
Snowboarder
Thermal
Energy
Energy
Sun
Capacity
for change
Light
Waves
Can’t create
or destroy
Radiation
Transfer it
Force
Work
Store it
X
Distance
Kinetic
Heat
Friction
Objects
in
motion
Snowboarder
 Thermal Energy is just energy
stored in the kinetic energy of
atoms
Thermal
Energy
Energy
Sun
for change
 How
is energy stored?
Capacity
Light
 Potential energy is energy stored because
Waves
of an object’s position
 Examples… Radiation
Can’t create
or destroy
Transfer it
 If you stretch a rubber band, it hasForce
more
energy than its starting position
X
Work
 An object at a higher position has Distance
more
energy than a similar object at a lower
Kinetic
position
Heat
Friction
 An electron in a higher orbit has more
energy than it did in a lower orbit
Objects
Store it
Potential
in
motion
 Electricity and magnetism are also forms
of potential energy
Snowboarder
Position
Gravitational
Elastic
Chemical
Spring or
Rubber
Band
Food
Battery,
TNT
Thermal
Energy
Sun
Capacity
for change
Energy
Light
Waves
Can’t create
or destroy
Radiation
Transfer it
Force
Work
Store it
X
Distance
Kinetic
Heat
Potential
Friction
Objects
in
motion
Position
Snowboarder
Gravitational
Elastic
Chemical
spring or
rubber band
Food
Battery,
TNT
Thermal
Energy
Energy Transfer Pie Chart
Store
Transfer
Electrical Energy - Eelec Work - W
Gravity Potential- PE
Heat - Q
Elastic Potential- Ee
Radiation
Chemical- Ec
Kinetic Energy – KE
Thermal Energy - Et
A
PE
A
B
C
B
Wgravity
Wfriction
PE
C
Et
KE
Wgravity
Wfriction
Et
KE
Practice and Demos

Create energy transfer pie charts
for the following processes:






Bending a paperclip (on your
own)
Movement of a pendulum
Solar Panel and motor
Spring and cart
Be sure to show what is causing
the energy to transfer.
Follow the instructions and use
the pie charts in the class set.
 Abbreviations
Store
•
PE – Gravity Potential
•
KE – Kinetic Energy
•
Ee – Elastic Energy
•
Echem – Chemical Energy
•
Et – Thermal Energy
•
Eelec – Electrical Energy
Transfer
•
W – Work
•
Q – Heat
•
R - Radiation
******Begin your homework if you finish early ******
Physics Part 2…
Force and Motion
Rolling Ball Grand Prix




Purpose: To observe an object in motion and determine what is
necessary to change that object’s motion.
Materials: Butcher paper with track, timer, and a large marble.
Procedure: See who can roll the ball along the track the fastest
using one finger.
Rules:




If the marble goes off the track
pick it up and restart where
the marble went out. Keep the
timer running
You can not touch the marble
at all in the “no touch” zone
Be sure to use only one finger
Answer the questions on the
sheet as you go.
Rolling Ball Grand Prix
1.
Describe the ball’s motion
in the “no touch” zone.


2.
What does the ball do in
the corners or around the
loop if you don’t push it?

3.
Moves in a straight line
Speed stays about the same
Wants to keep going in the
same direction
What can you say in
general about the motion
of an object that has no
“force”?

Without a force, objects will
move in a straight line at the
same speed
 This is basically
Newton’s 1st Law of
Motion…
“An object at rest tends to stay at
rest and an object in motion tends to
stay in motion with the same speed
and in the same direction unless
acted upon by an unbalanced force”
 This is also called the
Law of Inertia


Inertia is an object’s
resistance to a change
in motion
Mass is a measure of
inertia
Rolling Ball Grand Prix
4.
How did you get the ball to
speed up or slow down?


5.
Push Harder in the direction
it is rolling
Push opposite the motion
How did you get the ball to
change direction?

Push in the direction you
want the ball to go
 Force is any push or
pull on an object

 Acceleration (a) is the
rate of change in
velocity


6.
What would you need to
do differently if the ball
was twice as large (had
twice the mass)?

Push harder to get the same
change in motion
To change the ball’s
motion, you applied force
Velocity is an object’s
speed and direction
Force causes acceleration
which changes speed or
direction
 Mass measures inertia,
or resistance to change

More mass, less
acceleration
Rolling Ball Grand Prix
 Force is any push or
pull on an object

 This is the 2nd Law of
Motion:


Increase force…
increase acceleration
Increase mass…
decrease acceleration
Force
Acceleration 
mass
F
or a 
m
Force is measured in Newtons (N)
To change the ball’s
motion, you applied force
 Acceleration (a) is the
rate of change in
velocity


Velocity is an object’s
speed and direction
Force causes acceleration
which changes speed or
direction
 Mass measures inertia,
or resistance to change

More mass, less
acceleration
Rolling Ball Grand Prix
7.
Which of the following
would require the least
amount of force,
if applied to the same ball?
a)
b)
c)
d)
Stopping the ball that is
rolling on a flat and
smooth surface.
Changing the direction of
a ball that is rolling on a
flat and smooth surface.
Starting the ball in motion
on a flat and smooth
surface.
Keeping the ball moving
at a constant speed on a
flat and smooth surface.





Answer D
As the ball rolls there is
a small amount of
friction… if you don’t
keep pushing the ball
will slow
To keep the ball rolling,
at constant speed you
just need to overcome
friction
A, B, and C require a
change in motion
To change the balls
motion, you need to
overcome both inertia
and friction
Rolling Ball Grand Prix
7.
What would happen if two
object’s were racing on the
same track and they
collided?



Each would change speed
and/ or direction… requires
force
They exert force on each
other
The forces are in opposite
directions
Force
Force
 This is the 3rd Law of Motion…
“For every action there is an equal
and opposite reaction”
 Forces always occur in pairs
that are equal and in opposite
directions
Examples…
The earth exerts a 600N force on you, you exert
the same force on the earth
A Bat hits a ball, the ball hits the bat with the
same force
A hammer strikes a nail and drives the nail into a
block of wood. If the action force is the hammer
striking the nail, the reaction force is
a)
the nail striking the wood with an equal
and opposite force.
b)
the nail striking the hammer with an
equal and opposite force.
c)
the wood striking the hammer with an
equal and opposite force.
d)
the wood striking the nail with an equal
and opposite force.
Graphs of Motion
No acceleration
acceleration
velocity
distance
Constant acceleration
time
time
time
Force
What is a Net
force?
 Net Force = sum of all force vectors
Force
What is a Net
force?
 Net Force = sum of all force vectors
Balanced Forces…
•No Net Force
•What happens?
Unbalanced Forces…
•Net Force
•What happens?
*Nothing changes
*Cart will Accelerate to the right
Force
How are
forces
different?
 Types of forces:
 Contact forces- forces that
happen when two objects
touch
 Field Forces- objects don’t
touch but they still push or
pull each other (Action-at-adistance)
Types of Forces
Contact Forces
Field Forces
Frictional Force
Gravitational Force
Tensional Force
Electrical Force
Normal Force
Magnetic Force
Air Resistance Force
Applied Force
Spring Force
Field Forces
 Gravitational Force
 Any object with mass creates
gravitational force… more mass, more
force
 the closer the object, the greater the
force…
 The force decreases rapidly as distance
increases
Small force
Much
Bigger
force
Electrical force and
magnetism are the
same as gravity in
varying with distance
What we need to know…
1. Which of the following examples has the
greatest thermal (internal) energy?
a) 5 kg of water with a temperature of
150°C
b) 8 kg of water with a temperature of
110°C
c) 10 kg of water with a temperature of
90°C
d) 100 kg of water with a temperature
of 28°C
1.
Which of the following examples has the greatest
thermal (internal) energy?
a) 5 kg of water with a temperature of 150°C
b) 8 kg of water with a temperature of 110°C
c) 10 kg of water with a temperature of 90°C
d) 100 kg of water with a temperature of 28°C
D… temperature measures the average kinetic energy.
To determine the greatest amount of energy, you
need to consider mass or matter. Since it is all the
examples are the same substance, just multiply the
mass x temperature. Thermal energy is where all
energy in a physical process ends up… the random
motion of atoms and molecules… this point should be
emphasized since several sample test questions
allude to this.
2.
A ball is initially dropped from a height 4
meters. After the ball bounces it returns
to a height of only 2 meters. How much
of the ball’s initial gravitational potential
energy was transformed between the
initial position and the final position of
the ball?
a) One fourth of the total energy.
b) Half of the total energy.
c) Double the total energy.
d) Four times the total energy.
2. A ball is initially dropped from a height 4 meters. After the ball
bounces it returns to a height of only 2 meters. How much of
the ball’s initial gravitational potential energy was transformed
between the initial position and the final position of the ball?
a) One fourth of the total energy.
b) Half of the total energy.
c) Double the total energy.
d) Four times the total energy.
B… at the start the total energy equaled the
gravitational potential, so if the ball only
went ½ as high then only ½ the total was
transformed… the other ½ was transformed
into thermal energy.
3. Energy is created as the result which
activity?
a) Burning gasoline in an internal
combustion engine.
b) Damming a river for hydroelectric
power.
c) Rolling a marble down an incline plane.
d) Energy can only be transformed, not
created.
3.
Energy is created as the result which activity?
a) Burning gasoline in an internal combustion engine.
b) Damming a river for hydroelectric power.
c) Rolling a marble down an incline plane.
d) Energy can only be transformed, not created.
D… Energy cannot be created or destroyed, it can
only be stored or transferred. Total energy
remains constant, but different amounts can be
transferred between different storage means
like… thermal gravitational potential, kinetic,
electric potential, chemical potential, etc…
4.
Aluminum was once used as the wires in home construction.
Recently, it was changed to copper wires. Which of the
following statements BEST account for why aluminum was
replaced with copper?
a) When electrical energy is passed through a copper wire,
less of the energy removes copper atoms from the wire.
b) The electrical energy that a copper wire can transfer is
less than
an aluminum wire.
c) As a byproduct of transmission, more electrical energy is
transformed to wasted thermal energy in aluminum wire
than in copper
d) The electrical energy that passes through an aluminum
wire cannot be directed as well as the energy passing
through copper.
4.
Aluminum was once used as the wires in home construction. Recently, it
was changed to copper wires. Which of the following statements BEST
account for why aluminum was replaced with copper?
a) When electrical energy is passed through a copper wire, less of the
energy removes copper atoms from the wire.
b) The electrical energy that a copper wire can transfer is less than
an aluminum wire.
c)
As a byproduct of transmission, more electrical energy is transformed
to wasted thermal energy in aluminum wire than in copper
d) The electrical energy that passes through an aluminum wire cannot be
directed as well as the energy passing through copper.
C… In any process or activity, some
energy is lost as thermal energy.
To increase efficiency, we want to
minimize thermal losses.
5. In an alternating current (AC) circuit,
a) voltages can be easily increased and decreased
within the circuit allowing for lower energy
losses during transmission.
b) voltages change direction several times a
second to generate electrical charge more
rapidly.
c) rapid current changes regulate the ease at
which electricity passes through the circuit.
d) current most often is high to prevent energy
losses during transmission, but can be low to
decrease the voltage in the circuit.
5.
In an alternating current (AC) circuit,
a) voltages can be easily increased and decreased within the
circuit allowing for lower energy losses during transmission.
b) voltages change direction several times a second to generate
electrical charge more rapidly.
c) rapid current changes regulate the ease at which electricity
passes through the circuit.
d) current most often is high to prevent energy losses during
transmission, but can be low to decrease the voltage in the
circuit.
A… In any process or activity, some energy
is lost as thermal energy. To increase
efficiency, we want to minimize thermal
losses.
6. Which of the following describes how a dam
creates electricity?
a) Water is heated up and creates steam to turn
the generator to create electricity.
b) Gravitational potential energy transfers to
kinetic energy which turns a generator.
c) Electrons are removed from the water as it
passes and creates electricity.
d) Water flows over wires in the dam which
creates current from the water.
6.
Which of the following describes how a dam creates electricity?
a)
Water is heated up and creates steam to turn the generator to create electricity.
b)
Gravitational potential energy transfers to kinetic energy which turns a generator.
c)
Electrons are removed from the water as it passes and creates electricity.
d)
Water flows over wires in the dam which creates current from the water.
B… The vast majority of electricity we use is from generators.
Generators produce electricity by rotating a wire
(electrons) through a magnetic field. A generator can be
turned many ways… primarily we use steam pressure
(like steam shooting out of tea-kettle) or moving water
to turn a turbine (like a windmill or waterwheel). Our
powerplants use natural gas, nuclear fission, coal and oil
to create steam to turn a turbine. Dams convert the
gravitational energy stored in the water behind the dam
into kinetic energy of moving water, as moving water
turns the turbine which turns the generator.
7. A hammer strikes a nail and drives the nail into
a block of wood. If the action force is the
hammer striking the nail, the reaction force is
a) the nail striking the wood with an equal and
opposite force.
b) the nail striking the hammer with an equal
and opposite force.
c) the wood striking the hammer with an equal
and opposite force.
d) the wood striking the nail with an equal and
opposite force.
7.
A hammer strikes a nail and drives the nail into a block of
wood. If the action force is the hammer striking the nail, the
reaction force is
a) the nail striking the wood with an equal and opposite force.
b) the nail striking the hammer with an equal and opposite
force.
c) the wood striking the hammer with an equal and opposite
force.
d) the wood striking the nail with an equal and opposite force.
B… Newton’s 3rd Law, for every action, there is
an equal and opposite reaction. If you push
or pull (apply force) to something
(anything), that something will push or pull
on you in the opposite direction.
8.Which of the following would
supply the greatest
acceleration when applied to a
10 kg mass?
a)5N
b)10N
c)15N
d)20N
8.
Which of the following would supply the greatest acceleration
when applied to a 10 kg mass?
a) 5N
b) 10N
c) 15N
d) 20N
D… Newton’s 2nd Law simply stated Force equals
mass times acceleration. If force increases,
acceleration increase. If mass increases,
acceleration decreases. Force is measured in
Newtons (N), so 20N is the greatest force
giving the greatest acceleration.
9.
Use the diagram to answer the question below.
A cart is being pulled North across a
carpeted floor. Which direction is the
force of friction acting?
a)North
b)South
c) East
d)West
9.
Use the diagram to answer the question below.
A cart is being pulled North across a carpeted floor. Which direction is the force of
friction acting?
a) North
b) South
c) East
d) West
B… Friction always opposes the
applied force, so if a force is
pulling the block north, friction
would be pointing south.
10.You have created a track out of cardboard for a
marble to travel down. In order for the marble to
complete the track, why does the first hill have to
be the highest?
a) The friction caused by the track resists the
motion of the marble.
b) The friction caused by the track increases the
motion of the marble.
c) Gravity is pulling down on the marble causing it
to slow down.
d) Gravity is pulling down on the marble causing it
to speed up.
10. You have created a track out of cardboard for a marble to travel
down. In order for the marble to complete the track, why does the
first hill have to be the highest?
a) The friction caused by the track resists the motion of the marble.
b) The friction caused by the track increases the motion of the
marble.
c) Gravity is pulling down on the marble causing it to slow down.
d) Gravity is pulling down on the marble causing it to speed up.
A… Friction would oppose the motion caused by the force of
gravity this causes some of the gravitational potential
energy to be lost as thermal energy (like rubbing your
hands together). The marble now doesn’t have enough
energy to make it to the same height, so the 2nd hill needs
to be lower.
Questions?
Class Handouts and Homework
Word List
Energ
y
Capacity for change
Can’t create or
destroy
Store it
Transfer it
Kinetic
Potential
Position
X
Elastic
Gravitational
Chemical
Spring
Food
Snowboarder
Objects in motion
Battery
Sun
Radiation
Work
Heat
Waves light
Force
Distance
Friction
Thermal energy
Vibrating atoms and
molecules
1.
Paperclip
a)
b)
c)
d)
e)
Open the paperclip into a “V”
Touch the “V” to your upper lip. How does
it feel? Record observation:
__________________________________
Open and close (bend) the paperclip
rapidly at least 10 times and then
immediately touch it to your lip. Record
observation:
__________________________________
Touch the “V” to your lip again. Record
observation:
__________________________________
Use the pie charts below to show how the
energy was stored and transferred.
2.
Spring Cart
a)
b)
c)
d)
Compress the spring into the cart
Place the spring end of the cart against an
immoveable object and release spring
Record observations:
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
Use the pie charts below to show how the
energy was stored and transferred.
3.
Pendulum
a)
b)
c)
d)
e)
f)
g)
Pull the “bob” back about 30 degrees and
release.
Observe the motion for 10 cycles.
Where does the “bob have the most kinetic
energy?
__________________________________
Where does the “bob” have the most
potential energy?
__________________________________
What happens to the speed of the “bob”
over time?
__________________________________
Is there friction? What would happen if
there were no friction?
__________________________________
Use the pie charts below to show how the
energy was stored and transferred.
4.
Solar Panel and Motor
a)
b)
c)
d)
e)
f)
Turn on the light and move the solar panel
toward the light.
Record observations:
__________________________________
What happens as the panel is moved
closer to the light?
__________________________________
Does all of the energy from the light reach
the solar panel? Why or why not?
__________________________________
Use the pie charts below to show how the
energy was stored and transferred.
Why is the first pie chart bigger?
__________________________________