Transcript Motion

GHSGT
Physics Review
Motion
One possible unit of speed is ___.
a. miles per hour
b. kilometers per hour
c. light years per century
d. all of the above
e. none of the above
The answer is D.
Average Speed is a distance traveled divided
by the time required for the trip.
a. speed = distance / time
b. velocity = distance / time in a direction
c. An acceptable unit would be any measure
of length over any unit of time.
d. mi/hr, km/hr, and m/s are common units for
speed or velocity.
Motion
Acceleration is defined as the change in ___.
a. distance divided by the time interval
b. velocity divided by the time interval
c. time it takes to move from one speed to
another speed
d. time it takes to move from one place to
another place
e. velocity of an object
The answer is B.
Acceleration is the change in velocity divided
by the time it took to change the velocity.
a. acceleration = Δ velocity / Δ time
b. Acceleration tells how fast an object is
getting faster (or slower).
c. Acceleration also tells if an object is
changing direction.
d. The units for acceleration are a distance
over a time squared (i. e. m/s2).
Motion
Suppose you take a trip that covers 240 km
in 4 hours. Your average speed is ___.
a. 960 km/hr
b. 480 km/hr
c. 240 km/hr
d. 120 km/hr
e. 60 km/hr
The answer is E.
Speed = distance / time
Speed = 240 km / 4 hr
Speed = 60 km/hr
Newton’s Laws
A sheet of paper can be withdrawn from
under a carton of milk without toppling it if
the paper is pulled quickly. The reason this
can be done is that ___.
a. The milk carton has very little weight.
b. There is an action/reaction pair operating.
c. Gravity pulls very hard on the milk carton.
d. The milk carton has inertia.
e. none of the above
The answer is D.
Newton’s first law states that an object tends
to retain its current state of motion unless acted
on by a net force. This is the law of inertia.
a. More massive objects have more inertia
because they are better at resisting
changes in motion.
b. There was not enough friction to move the
milk carton with the paper.
Newton’s Laws
Compared to its weight on the earth, a 10 kg
object on the moon will weigh ___.
a. less
b. more
c. the same amount
The answer is A.
Weight is the force that an object experiences
due to gravity. An object’s weight changes
depending upon where it is (i. e. on the earth,
on the moon, or on Mars).
a. The units for any force are Newtons.
Mass is the amount of stuff in an object. An
object’s mass never changes no matter where
its located.
a. measured in kilograms.
Newton’s Laws
Newton’s second law states that force is
proportional to both mass and acceleration
(F = m a).
a. The acceleration due to gravity on the
moon is less than that on earth, therefore
the object will have a smaller weight.
b. mass and weight are often confused. An
object will have the same mass (amount
of stuff) on both the earth and the moon.
Newton’s Laws
Newton’s third law states that, for every action,
there is an equal and opposite reaction.
a. Forces always act in pairs. For example, if
you kick a football, your foot applies a force
to the football. However, the football
applies an equal and opposite force to your
foot.
Newton’s Laws
Friction ___.
a. acts in a direction that opposes the motion
of an object.
b. comes from microscopic bumps that act as
obstructions to the object’s motion.
c. is the name given to the force acting
between surfaces sliding between one
another.
d. all of the above
e. none of the above
The answer is D.
Friction is the force that exists between
contacting objects moving past one another.
a. It is caused by interactions between the
objects on a microscopic scale, as in the
diagram below.
b. Friction on an object is always opposite the
direction of the object’s motion.
c. The units for friction, as for any
force, are Newtons.
Momentum
Which has more momentum, a large truck
moving at 30 miles per hour or a small truck
moving at 30 miles per hour?
a. the large truck
b. the small truck
c. Both trucks have the same momentum.
The answer is A.
The momentum of an object is the product of an
object’s mass and velocity.
a. Momentum (p) = (mass) (velocity)
b. The units of momentum are kg m/s.
c. Since the trucks have the same velocity,
the one with the larger mass has the larger
momentum.
Momentum
A 4 kg ball has a momentum of 12 kg m/s. What
is the ball’s speed?
a. 3 m/s
b. 4 m/s
c. 12 m/s
d. 48 m/s
e. none of the above
The answer is A.
p = (m) (v)
v=p/m
v = 12 kg m/s / 4 kg
v = 3 m/s
Work
If Harry pushes an object with twice the force
for twice the distance, he does ___.
a. the same work
b. twice the work
c. four times the work
d. eight times the work
The answer is C.
Work is the force times the distance over which
the force acts.
a. Work= (force) (distance)
b. The units for work are Joules.
b. Since there was 2 times as much force and
2 times as much distance.
c. W = (2F) (2d)
d. W = 4 (F) (d)
e. The amount of work he did increased by a
factor of 4.
Power
If Lydia pushes a red box that weighs 10 N for 5
m across a room in 10 seconds, and she
pushes a blue box that weighs 10 N for 5 m
across the same room in 5 seconds, with which
box did she use more power?
a. the red box
b. the blue box
c. She expended the same amount of power
for both boxes.
The answer is B
Power is the work applied divided by the
amount of time it took to perform the work.
a. The units for power are Watts.
b. Power = work / time
c. Power = (10 N) (5 m) / 5 s
Power = 10 Watts for the blue box (B)
d. Power = (10 N) (5 m) / 10 s
Power = 5 Watts for the red box
Energy
As a pendulum swings back and forth ___.
a. Potential energy is transformed into kinetic
energy.
b. Kinetic energy is transformed into potential
energy.
c. At the lowest part of the swing, its energy is
all kinetic.
d. At the end points of the swing, its energy is
all potential.
e. all of the above
The Answer is E
Kinetic energy is energy of motion.
Potential energy is stored energy or energy of
position.
a. The pendulum is at rest at the top of its
swing. It has no kinetic energy, but much
gravitational potential energy.
b. The units for work, kinetic
energy and potential
energy are Joules.
The answer is E.
b. At the bottom of its swing, it has no
potential energy because the potential
energy has been converted to kinetic
energy. (it is moving fast!)
Simple Machines
The ratio of output force to input force in a
simple machine is called the ___.
a. fulcrum
b. pivot point
c. efficiency
d. mechanical advantage
e. lever arm
The answer is D.
Mechanical advantage tells you how much a
machine multiplies the force you apply.
a. MA = output force / input force
b. Nothing is free! The trade-off is that you
apply a small force over a large distance to
apply a large output force over a small
distance. Think about a wrench or a ramp.
c. The amount of work (force times distance)
remains relatively constant with any loss
due to friction.
Heat Transfer
Heat transfer by conduction occurs when ___.
a. Electrons bump into atoms and other
electrons.
b. Large numbers of atoms move from place
to place.
c. Atoms give off heat in the form of
electromagnetic waves.
d. Electromagnetic waves travel from one
place to another through a vacuum.
e. none of the above
The answer is A
Conduction is the transfer of energy as
particles and molecules collide with each other.
To do this, the objects have to touch.
conduction
Heat Transfer
Heat transfer by convection occurs when ___.
a. Electrons bump into other electrons.
b. Large numbers of atoms move from place
to place.
c. Atoms give off heat in the form of
electromagnetic waves.
d. Electromagnetic waves travel from one
place to another through a vacuum.
e. none of the above
The answer is B.
Convection is the bulk movement of heated or
cooled material within a sample, as in warm air
rising and cool air sinking.
convection currents in boiling water
Heat Transfer
Heat travels from the sun to the earth by ___.
a. conduction
b. convection
c. radiation
d. insulation
e. vacuumization
The answer is C.
Electromagnetic radiation is emitted by the sun,
some of which encounters the earth, adding
energy to the matter of the earth.
a. Radiation is the transfer of energy by the
emitting of electromagnetic radiation which
is then absorbed by another object.
Phase Changes
Evaporation occurs when matter changes from
a ___.
a. gas to a solid, b. gas to a liquid
c. solid to a liquid, d. solid to a gas
e. liquid to a gas
Condensation occurs when matter changes
from a ___.
a. gas to a solid, b. gas to a liquid
c. solid to a liquid, d. solid to a gas
e. liquid to a gas
The answers are E then B.
A phase change is accompanied by the
absorption or the release of energy.
a. A diagram for water with common phase
change terms is provided below.
Waves
The distance between successive identical
parts of a wave is called its ___.
a. frequency
b. period
c. wavelength
d. velocity
e. amplitude
The answer is C.
Wavelength is the distance from crest to crest
or trough to trough, measured in meters.
Amplitude is the size of the disturbance, from
center to peak or center to trough.
Frequency is how many time the disturbance
occurs per unit time, typically in cycles per
second or Hertz.
Waves
Sound waves cannot travel in ___.
a. air
b. water
c. steel
d. a vacuum
e. Sound can travel in all of the above.
The answer is D.
Sound is a mechanical wave. It requires a
medium, or matter, to travel through.
Electromagnetic waves do not need a medium
to travel through. Electromagnetic waves from
the sun travel to the earth through the nearvacuum that is outer space.
Waves
If the sun were to disappear right now, we
wouldn’t know about it for about 8 minutes
because it takes 8 minutes ___.
a. for the sun to disappear
b. to operate receiving equipment in the dark
c. for light to travel from the sun to the earth
d. all of the above
e. none of the above
The answer is C.
Waves travel at a certain speed. Wavelength
and frequency are related to speed.
a. Wave speed = (frequency) (wavelength)
b. Electromagnetic radiation travels at the
speed of light (c) which is 3 x 108 m/s or
186,000 miles per second. The sun is
so far away that it takes almost 8 minutes
for these waves to reach the earth.
c. Mechanical wave speed depends on the
matter it is traveling in. Sound is faster in
solids than liquids and slowest in gases.
Light
Different colors of light correspond to different
light ___.
a. velocities
b. intensities
c. polarities
d. frequencies
e. none of the above
The answer is D.
Our eyes interpret the frequency of light as
color.
Because frequency is related to wavelength by
speed, another acceptable answer could be
wavelength. However, this was not one of the
choices.
Light and Color
Complimentary colors are two colors that ___.
a. look good together
b. are primary colors
c. are next to each other on the color chart
d. produce white light when added together
e. none of the above
The answer is D.
Light’s primary colors are red, green, and
blue.
a. Red and green light make yellow light.
b. Blue and red light make magenta light.
c. Blue and green light make cyan light.
d. Red, green, and blue light combine to make
white light.
Light and Color
d. Hence, a primary light color and its
complementary color will create white light.
e. Light colors opposite each other on the
wheel here produce white light.
Electric Charge
Two like charges ___.
a. attract each other
b. repel each other
c. neutralize each other
d. have no effect on each other
e. must be neutrons
The answer is B.
Charges that have the same sign (negative /
negative or positive / positive) will repel each
other whereas charges that have opposite signs
(negative / positive) will attract each other.
Electricity
A 10 Ω resistor has a 5 A current running
through it. What is the voltage across the
resistor?
a. 5 V
b. 10 V
c. 15 V
d. 20 V
e. more than 20 V
The answer is E.
Ohm’s Law states that voltage = (current)
(resistance)
a. Voltage = (I) (R)
b. I is the symbol for current. Current is
measured in amps (A).
c. R is the symbol for resistance. Resistance
is measured in Ohms (Ω)
d. V = (I) (R)
V = (5 A) (10 Ω)
V = 50 Volts
Electricity
To form an electric circuit, you need ___.
a. a power source
b. some resistance (i. e. a light bulb)
c. wires or conductors to connect everything
d. a complete path for the current
e. all of the above
The answer is E.
A complete circuit needs a voltage source (like
a battery), wires to connect all of the
components, and a load to consume the energy
(such as a light bulb or your IPOD).
Electric Circuits
The total resistance of a 3 Ω resistor and a 6 Ω
resistor in series is ___.
a. 18 Ω
b. 9 Ω
c. 6 Ω
d. 3 Ω
e. 2 Ω
The answer is B.
For resistors in series, add the resistances
together to determine total resistance.
1
1 parallel,
1
For resistors
in
add the inverses of each


...
R
R
resistor to
getR the
inverse of the total resistance.
total
1
2
This problem involved a series
circuit.
Rtotal = R1 + R2
Rtotal = 3 ohms + 6 ohms
Rtotal = 9 ohms
series
parallel
Electric Circuits
Equation for adding the resistors in a series
circuit.
Rtotal = R1 + R2 + R3 . . . .
Equation for adding the resistors in a parallel
circuit.
1 + 1 + 1 .....
1
=
Rtotal R1 R2 R3
End of GHSGT
Physics Review