Final Review Concepts of Physics
Review Part II – Chapters 8-14
Work & Power
1) In physics, work is defined as
A) force times time.
B) force divided by time.
C). force times distance.
D) force divided by distance.
E) distance divided by time.
2) If you lift two loads up one story, how much work do you do compared to lifting just one load up one story?
A) Four times as much
B) Twice as much
C) The same amount
D) Onehalfasmuch
E) One quarter as much
3) If you lift one load up two stories, how much work do you do compared tolifting one load up only one story?
A) Four times as much
B) Twice as much
C) The same amount
D) One half as much
E) One quarter as much
4) How many joules of work are done on an object when a force of 10 N pushesit5m?
A) 50 J
B) 10J
C) 5J
D) 2 J
E) 1 J
5) The unit of work is the
A) newton
B) watt
C) meter
D) joule
E) second
6) How much power is required to do 100 J of work on an object in 2 seconds?
A) 200W
B) 100W
C) 5OW
D)2W
E) OW
7) The unit of power is the
A) newton.B) wattC) meter
D) joule.E)second
8) Potential energy is the energy an object has because of its
A) speed.
B) location.
C) size.
D) temperature
E) density.
9) The amount of potential energy possessed by an elevated object is equal to
A) the force needed to lift it.
B) the distance it is lifted.
C) thepower used to lift it.
D) the work done in lifting it.
E) the value of the acceleration due to gravity.
10) How much work is done on a 50-N rock that you carry horizontally across a 10 m room?
A) 500 J
B) 50 J
C) 10 J
D) 5 J
E) 0 J
11) How much work is done on a 50-N rock that you lift 10 m?
A) 500 JD) 1 J
B) 50 JE) O J
C) 10 J
Universal Gravitation
12) Why did Newton think there was a force acting on the moon?
A) Because the moon always keeps one side toward the earth
B) Because the moon moves in a curved path
C) Becausethere is no air onthemoon
D) Because the moon is moving
E) Alloftheabove
13) Newton had the insight to see that the
A) moon always keeps one side toward the earth.
B) moon orbits the earth.
C) moon is moving.
D) force on the moon has the same nature as the force on an apple
E) None of theabove
14) Since the earth is attracted to the sun, why doesn’t it fall into the sun?
A) Because it has a large tangential velocity
B) Because there is an equal Force holding it away from the sun
C) Because it has too much mass to move toward the sun
D) Because it has too much inertia to move toward the sun
E) Allof the above
15) The gravitational Force between two masses
A) is always an attraction.
B) depends on how largethe masses are.
C) depends inversely on the square of the distances between the masses.
D) depends on a universal gravitational constant.
E) All of the above
16) Gravitational forces are the weakest forces found in nature because of this.
A) we cannot see the gravitational effect between a pencil and the earth.
B) there is no gravitational force between two 1-kg masses.
C) there is no movement between two 1-kg masses located near each other in space.
D) we can see gravitational effects only when a large mass is involved.
E) gravitational forces between protons do not exist
17) Suppose the gravitational force between two masses is 10-N. If the distance between the massesis cut in half, what is the force between the masses?
A)40N
B)20N
C)10 N
D)5N
E)2.SN
18) Suppose the gravitational force between two masses is 10-N. If the distance between the masses is doubled, what is the force between the masses?
A)40N
8)20 N
C) 10 N
D) 5 N
E)2.5 N
19) Suppose the gravitational force between two masses is 10-N. If the magnitude of each mass doubles, what is the force between the masses?
A)40N
B)20N
C)1ON
D) 5 N
E) 2.5 N
20) The component of an orbiting satellite’svelocity parallel to the earth’s surface is called its tangential velocity. (T or F)
21) The force of attraction between two masses depends inversely on the square of the distance between the masses. Any law that has this kind of dependence on distance is called an inverse square law. (T or F)
Gravitational Effects
22) The value of the acceleration due to gravity, g.
A)dependson the radius of the earth.
B)dependsonthemass of the earth
C)depends on the universal gravitational constant. G.
D)is differenton different planets.
E)Allofthe above
23) if the earth had twice its present mass, but the same radius, what would be
the value of g?
A) 39.2 m/s/s
B) 19.6 m/s/s
C)9.8 m/s/s
D)4.9m/s/s
E) 0 m/s/s
24) If the radius of the earth were one half what it is now, and the mass were
the same, what would be the value of g?
A) 39.2 m/s/s
B) 19.6 m/s/s
C)9.8m/s/s
D) 4.9 m/s/s
E) 0 m/s/s
25) We can tell if a gravitational force exists in a region of space if
A) we let go of a ball and it starts to move.
B) we disturb a pendulum and it starts swinging.
C) a force exists on a mass placed there
D) we can weigh ourselves.
E) All of theabove
26) Gravitational field lines show the
A) direction a mass would be accelerated.
B) direction of the field at each point.
C) direction of the force on any mass.
D) strength of the Field.
E) Alloftheabove
27) The gravitational field strength at the center of the earth is
A) large.
B) the same as on the surface.
C) smaller than on the surface but still larger than zero.
D) zero.
28) If you were to weigh yourself in an elevator that is accelerating upward.
compared to your ordinary weight you would weigh
A) more.
B) thesame.
C) less, but more than zero.
D) zero.
29) A straight line around which rotation takes place is called an axis. (T or F)
30) The rotational speed of a wheel is the number of rotations it makes in a 10-second interval. (T or F)
31) Any force that causes an object to move in a circular path is called a centripetal force. (T or F)
32) Centrifugal forces are forces we invent to explain the effects of inertia in a
rotating reference frame. (T or F)
33) It is possible to rotate a very large cylindrical space habitat around its
central axis at just the right speed so people living inside the cylinder will
experience a force that feels like gravity. (T or F)
34) Theonly reason riders on a rotating platform in a carnival ride don’t fall out is because they are strapped in. (T or F)
35) A bugona turningrecordwillmake more turns perminuteifitwalks
toward the center of the record. (T or F)
36) When you whirl a can on the end of a string, the centripetal force on the
can is actually the pull of the string on the can. (T or F)
37) Ladybugs on the inside of a spinning bicycle tire mayexperience a force that feels like gravity to them. (T or F)
Rotational Mechanics
38)Torque isdefined as
A) mass times velocity.D) mass times acceleration.
B) force times time.E) momentum times radius.
C) force times lever arm
39) Suppose you try loosening a nut with a wrench, and the nut doesn’t give at
all. To loosen the nut you could
A) extend the lever-arm.
B) be sure to exert force perpendicular to the lever arm.
C) exert a larger force.
D) havea friend help you pullon the wrench.
E) Allof the above
40) Why are door knobs placed at the edge of a door rather than in the center?
A) becauseits closer to the edge of the doorway.
B) To help give more momentum to the door
C) Because it looks better there
D) To increase the force on the door
E) To increase the lever- arm
41) A meter stick is balanced at the 50-cm mark. You tie a 20-N weight at the
30-cm mark. Where should a 30-N weight be placed so the meter stick will
again be balanced?
A) 20 cm mark
B) 30cmmark
C) 50cm mark
D) 70cm mark
E) 80cm mark
42) lf youwere to weigh yourself in an elevator that is in free fall, compared to your ordinary weight, you would weigh
A) more.
B) thesame
C) less, butmorethan zero.
D) zero
43) To be truly weightless you would have to be
A) in free fall
B) in a satellite orbiting the earth.
C) onthemoon.
D) faraway from any planet or star.
E) All of theabove
Circular Motion
44) Which has greater linear speed a horse near the outside rail of a merry-go-round or a horse near the inside rail?
A) The outside horse
B) The inside horse
C) Neither—they both have the same linear speed.
45) Which has greater angular speed, a horse near the outside rail of a merry-go- round or a horse near the inside rail?
A) The outside horse
B) Theinside horse
C) Neither—they both have the same angular speed.
46) Which of the following is NOT a unit of rotational speed?
A) Revolutions per second
B) Rotations per second
C) Revolutions per minute
D) Meters per second
E)Rotations per minute
47) Whatisthedirection of the force that act on clothes in the spin cycle of a washing machine?
A) OutwardB) InwardC) UpD) Down
48) Atincanwhirledontheendofa string movesina circle because
A) once the can starts moving, that is its natural tendency.
B) the can continually pulls on the string.
C) there is a force on the can pulling it outward.
D) there is an inward force acting on the can.
E) Alloftheabove
49) If youwhirlatincanonthe end of astringand thestringsuddenly breaks.
the can will
A)fly directly away from you.
B)flydirectlytowardyou.
C)fly off, tangent to its circular path.
D)spiral away from your hand.
E)spiral in toward your hand.
50) lf a football is kicked so the force on the ball is through its center of gravity, the ball will
A) tumble end over end in the air
B) spinaboutits axis in the air
C) move without any tumbling or spinning.
D) not even get into the air.
E) deflate
51) The resistance of an object to changes in its rotational state of motion is called rotational
A) momentum.
B) inertia.
C) torque
D) acceleration.
E) velocity
52) Which has more rotational inertia, a bicycle wheel or a solid disk of the same mass and diameter?
A) The wheel.
B) Thedisk
C) They both have the same rotational inertia.
53) Which has more rotational inertia, a girl running with her legs bent or the same girl running with her legs straight?
A) With bent legs
B) With straight legs
C) Both have the same rotational inertia
54) Which objects roll down an incline with the greatest acceleration?
A) Objects with large rotational inertia
B) Objects with small rotational inertia
C) Acceleration is independent of rotational inertia in this case.
55) Any solid cylinder will roll down an incline with greater acceleration than any hollow cylinder if
A) the mass of the solid cylinder is large.
B) the diameter of the solid cylinder is small.
C) the diameter of the solid cylinder is Large.
D) the mass of the solid cylinder is small
E) The solid cylinder always wins regardless of masses or diameters.
56) A person’s rotational inertia is least about
A) the person’s longitudinal axis.
B) the person’s transverse axis.
C) the person’s median axis.
D) an axis through the persons hands.
E) anaxisthroughthe person’s feet.
57) When a gymnast goes from an extended position to a tucked position, she
A) increases her rotational inertia.
B) decreases her rotational inertia.
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