Deck 3: Momentum and Energy

Question 1

An object in motion is an object that has

A)acceleration.
B)impulse.
C)momentum.
D)all of the above
E)none of the above

Answer 1

C

Question 2

It is correct to say that impulse is equal to

A)momentum.
B)the change in momentum.
C)the force multiplied by the distance the force acts.
D)all of the above
E)none of the above

Answer 2

B

Question 3

A heavy truck and a small truck roll down a hill.Neglecting friction,at the bottom of the hill the heavy truck has greater

A)speed.
B)acceleration.
C)momentum.
D)all of the above
E)none of the above

Answer 3

C

Question 4

When Peter tosses an egg against a sagging sheet,the egg doesn't break due to

A)reduced impulse.
B)reduced momentum.
C)both of these
D)neither of these

Question 5

When you ride your scooter you have momentum.When you ride twice as fast you have

A)almost twice the momentum.
B)twice the momentum.
C)four times the momentum.
D)none of the above

Question 6

Which of the following has the largest momentum relative to Earth?

A)a tightrope walker crossing Niagara Falls
B)a pickup truck speeding along a highway
C)a Mack truck parked in a lot
D)a dog running down the street

Question 7

The change in momentum of an object is equal to the

A)force acting on it.
B)change in its velocity.
C)object's mass times the force acting on it.
D)impulse that acts on it.
E)all of the above

Question 8

What is the mass of a ball moving at 4 m/s with a momentum of 48 kg∙m/s?

A)4 kg
B)12 kg
C)48 kg
D)192 kg
E)none of the above

Question 9

To catch a fast-moving softball with your bare hand,you extend your hand forward just before the catch and then let the ball ride backward with your hand.Doing this reduces the catching force because the

A)relative velocity is less.
B)relative velocity is more.
C)time of catch is increased.
D)time of the catch is decreased.
E)none of the above

Question 10

A freight train rolls along a track with considerable momentum.If it rolls at the same speed but has twice as much mass,its momentum is

A)zero.
B)doubled.
C)quadrupled.
D)unchanged.

Question 11

When you simultaneously drop a light tennis ball and a heavy bowling ball,they hit the floor

A)at the same speed.
B)with the same force.
C)with the same momentum.
D)all of the above
E)none of the above

Question 12

Which has the greater momentum when moving?

A)a container ship
B)a bullet
C)either of these depending on speed

Question 13

The impulse-momentum relationship is a direct result of

A)Newton's first law.
B)Newton's second law.
C)Newton's third law.

Question 14

Bronco's speed increases after he dives from a hovering helicopter.Relative to an observer in the helicopter Bronco's momentum

A)also increases.
B)remains unchanged.
C)decreases.

Question 15

What is the speed of a 6-kg ball with a momentum of 72 kg∙m/s?

A)3 m/s
B)4 m/s
C)12 m/s
D)48 m/s
E)none of the above

Question 16

The force of a falling apple hitting the ground depends upon

A)the speed of the apple just before it hits the ground.
B)the time of contact with the ground.
C)whether or not the apple bounces.
D)all of the above

Question 17

What is the speed of a 4-kg ball with a momentum of 12 kg∙m/s?

A)3 m/s
B)4 m/s
C)12 m/s
D)48 m/s
E)none of the above

Question 18

An iron ball and wooden ball of the same size are dropped simultaneously from a tower and reach the ground at the same time.The iron ball has a greater

A)speed.
B)acceleration.
C)momentum.
D)all of the above
E)none of the above

Question 19

The distinction between impulse and force involves the

A)distance the force acts.
B)time the force acts.
C)difference between acceleration and velocity.
D)mass and its effect on resisting a change in momentum.

Question 20

What is the mass of a ball moving at 3 m/s with a momentum of 48 kg∙m/s?

A)4 kg
B)12 kg
C)16 kg
D)144 kg
E)none of these

Question 21

A fan attached to an ice sailcraft stalled on a windless day blows air into the sail that bounces backward upon impact.The boat

A)moves in the direction of the wind impact force.
B)does not move by this wind impact.
C)moves,but in the opposite direction of the wind impact force.

Question 22

When a boxer moves into an oncoming punch,the force experienced is

A)decreased.
B)increased.
C)no different,but the timing is different.
D)all of the above

Question 23

When you jump from an elevated position you usually bend your knees upon reaching the ground.By doing this,the contact time is about 10 times more than for a stiff-legged landing and the average force your body experiences is reduced by

A)less than 10 times.
B)more than 10 times.
C)about 10 times.

Question 24

According to the impulse-momentum relationship Ft = change in mv,a falling bungee jumper has momentum which is reduced by the force F exerted by the bungee cord.If v is the speed of the jumper,then m in the equation is the mass of the

A)jumper.
B)cord.
C)ground below.
D)none of the above

Question 25

Whether a truck comes to a stop by crashing into a haystack or a brick wall,the impulse is

A)greater with the haystack.
B)greater with the brick wall.
C)both the same

Question 26

A car traveling along the highway brakes to a stop.A greater braking force is required when the car has

A)more mass.
B)more momentum.
C)less stopping distance.
D)all of the above
E)none of the above

Question 27

Padded dashboards in cars are safer in an accident than non-padded ones because a person hitting the dash has

A)increased time of contact.
B)decreased contact force.
C)both of these
D)neither of these

Question 28

Which of these two collisions is more damaging; driving into a concrete wall with no "give," or colliding head-on with an identical car moving toward you at your same speed?

A)collision with the car
B)collision with the wall
C)both the same

Question 29

Whether a truck comes to a stop by crashing into a haystack or a brick wall,the stopping force is

A)greater with the haystack.
B)greater with the brick wall.
C)both the same

Question 30

The conservation of momentum is most closely related to Newton's

A)first law.
B)second law.
C)third law.

Question 31

A boxer punches a sheet of paper in midair from rest to a speed of 40 m/s in 0.05 s.If the mass of the paper is 0.01 kg,the force of the punch on the paper is

A)0.08 N.
B)0.8 N.
C)8.0 N.
D)80 N.

Question 32

A 1000-kg truck moving at 10 m/s that brakes to a stop in 5 s has an average braking force of

A)1000 N.
B)2000 N.
C)3000 N.
D)4000 N.
E)5000 N.

Question 33

The greater efficiency achieved with the curved blades of a Pelton wheel is due to

A)bouncing.
B)greater time of water impact.
C)rotational momentum.
D)divided impulse.

Question 34

When you can't escape being hit by a fast-moving object,you'll suffer a smaller force if the collision time is

A)long.
B)short.
C)the same way either way

Question 35

The force of air impact upon the sail of a boat is greater if the air

A)bounces upon impact.
B)encounters the sail head-on.
C)encounters the sail at a grazing angle.

Question 36

When a boxer is moving away from a punch,the force experienced is reduced because

A)momentum transfer is reduced.
B)the time of contact is increased.
C)the force is less effective.
D)all of the above

Question 37

Compared with falling on a wooden floor,a wine glass may not break when it falls on a carpeted floor because of

A)lesser impulse in stopping.
B)longer time to stop.
C)both of these
D)none of the above

Question 38

A karate chop is more effective if one's hand

A)follows through upon impact.
B)bounces upon impact.
C)extends the time upon impact.

Question 39

According to the impulse-momentum relationship Ft = change in mv,a falling baseball hits a player with a force F.The t in the equation is the time

A)the ball falls before hitting the player.
B)of contact of the ball hitting the player.
C)of reflex as the player responds to being hit.
D)all of the above
E)none of the above

Question 40

A karate expert executes a swift blow and breaks a cement block with her bare hand.The magnitude of the force on her hand is

A)zero.
B)less than the force applied to the cement block.
C)the same as the force applied to the block.
D)more than the force applied to the block.
E)need more information

Question 41

A heavy truck and a small car roll down a hill at the same speed and need to stop in the same amount of time.Compared with the force to stop the car,the force needed to stop the truck is

A)greater.
B)smaller.
C)the same.

Question 42

An astronaut floating alone in outer space throws a baseball.If the ball moves away at 20 m/s,the astronaut will move in the opposite direction at

A)20 m/s.
B)a lower speed.
C)a higher speed.
D)more information needed
E)none of the above

Question 43

The speed of a bullet fired from a gun will be about the same as the speed of the recoiling gun

A)when momentum is conserved.
B)because velocity is conserved.
C)when both velocity and momentum are conserved.
D)if the masses of the bullet and gun are equal.
E)none of the above

Question 44

While driving down the highway a lovebug spatters onto your windshield.Which experiences the greater force of impact?

A)the lovebug
B)your car
C)both the same but with different consequences

Question 45

If a monkey floating in outer space throws his hat away,the hat and the monkey will both move

A)away from each other,but at different speeds.
B)away from each other at the same speed.
C)a short distance and then slow down.
D)a short distance and then gain speed.
E)quickly to a stop.

Question 46

While driving down the highway a lovebug spatters onto your windshield.Which undergoes the greater impulse?

A)the lovebug
B)your car
C)both the same

Question 47

When bullets are fired in a forward direction from a fighter aircraft,the momentum of the aircraft

A)decreases.
B)is unchanged.
C)increases.

Question 48

A sandbag is motionless in outer space.A second sandbag with 3 times the mass moving at 12 m/s collides with it and they both stick together and move at a speed of

A)3 m/s.
B)4 m/s.
C)6 m/s.
D)8 m/s.
E)none of the above

Question 49

Two billiard balls having the same mass roll toward each other at the same speed.What is the net momentum of the two-ball system?

A)0 kg∙m/s
B)10 kg∙m/s
C)not enough information

Question 50

Jogging Jake runs along the top of a moving flatcar in the direction of motion of the flatcar.If he runs in the opposite direction,the combined momentum of Jake and the flatcar relative to an observer at rest will be

A)more.
B)the same.
C)less.

Question 51

Consider a gun with a pellet that is more massive than the gun.The firing speed is greater for the

A)pellet.
B)recoiling gun.
C)both are the same
D)none of the above

Question 52

When a cannon fires a cannonball at a given speed,the smaller recoil speed of the cannon is due to differences in

A)forces.
B)times.
C)masses.
D)momenta.

Question 53

When Jean standing on slippery ice catches her leaping dog Daisy,the momentum of both Jean and Daisy after the catch is

A)greater than their combined momentum before the catch.
B)equal to their combined momentum before the catch.
C)somewhat less than their combined momentum before the catch.

Question 54

A 5000-kg freight car crashes into a 10,000-kg freight car at rest.They couple upon collision and move with a speed of 2 m/s.What was the initial speed of the 5000-kg freight car?

A)4 m/s
B)5 m/s
C)6 m/s
D)8 m/s
E)none of the above

Question 55

Two identical freight cars roll without friction towards each other on a level track.One car rolls at 2 m/s and the other car rolls at 1 m/s.After the cars collide,they couple and roll together with a speed of

A)0.5 m/s.
B)0.33 m/s.
C)0.67 m/s.
D)1.0 m/s.
E)none of the above

Question 56

A cannonball fired from a long-barrel cannon will have a greater muzzle velocity because the cannonball receives a greater

A)force.
B)impulse.
C)both of these
D)none of the above

Question 57

A straw is used for a pea shooter.When you blow through the straw the speed of the emerging pea will be greater if the straw is

A)cut in half.
B)full length.
C)either cut in half or full length.

Question 58

The force that accelerates a rocket in outer space is exerted on the rocket by the

A)rocket's engine.
B)rocket's wings.
C)atmospheric pressure.
D)exhaust gases.
E)none of the above

Question 59

While driving down the highway a lovebug spatters onto your windshield.Which undergoes the greater change in momentum during the time of contact?

A)the lovebug
B)your car
C)both the same

Question 60

A 2-kg rifle is horizontally suspended by a pair of strings so that recoil can be measured.The rifle fires a 0.001-kg bullet at a speed of 200 m/s.The recoil velocity of the rifle is about

A)0.001 m/s.
B)0.01 m/s.
C)0.1 m/s.
D)1 m/s.
E)none of the above

Question 61

A 0.5-kg blob of clay moving at 2.0 m/s slams into a 4.0-kg blob of clay at rest.The speed of the two blobs stuck together after colliding is about

A)1.1 m/s.
B)1.5 m/s.
C)2.5 m/s.
D)none of the above

Question 62

Consider gliders that slide friction-free along a horizontal air track.Glider A has a mass of 1 kg,a speed of 1 m/s,and collides with glider B,which has a mass of 5 kg and is at rest.If they stick upon collision the combined-glider speed will be

A)1/4 m/s.
B)1/5 m/s.
C)1/6 m/s.
D)1 m/s.
E)none of the above

Question 63

When an apple falls to the ground,momentum is transferred to the ground.The momentum absorbed by the ground is

A)negligible compared to the momentum of the apple.
B)greater if the apple bounces.
C)greater than that of the apple whether or not bouncing occurs.
D)none of the above

Question 64

Whereas impulse involves the time that a force acts,work involves the

A)distance that a force acts.
B)time and distance that a force acts.
C)acceleration that a force produces.

Question 65

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard,the speed of the skateboard

A)decreases.
B)increases.
C)neither decreases nor increases.

Question 66

Two identical gliders slide toward each other on an air track.One glider moves at 1 m/s and the other glider moves at 2 m/s.They collide,stick,and move at

A)1/2 m/s.
B)1/3 m/s.
C)1/6 m/s.
D)3/4 m/s.
E)1.5 m/s.

Question 67

Just after a big fish swallows a small fish,the momentum of the two-fish system is

A)greater after lunch than before.
B)the same before and after lunch.
C)somewhat less after lunch.

Question 68

When a 100-kg astronaut ejects 0.1 kg of gas at a speed of 50 m/s from her propulsion pistol,her recoil speed is

A)50 m/s.
B)5.0 m/s.
C)0.5 m/s.
D)0.05 m/s.

Question 69

A 30-kg girl on friction-free roller blades pushes away a 25-kg boy also on roller blades at 1 m/s.The girl's speed is

A)0.45 m/s.
B)0.55 m/s.
C)0.83 m/s.
D)1.2 m/s.

Question 70

A 1-kg chunk of putty moving at 1 m/s collides and sticks to a 5-kg bowling ball initially at rest.The bowling ball and putty move with a momentum of

A)0 kg∙m/s.
B)1 kg∙m/s.
C)2 kg∙m/s.
D)5 kg∙m/s.
E)more than 5 kg∙m/s.

Question 71

The total momentum of a flock of identical birds could be zero only if the birds are

A)taking off from the ground.
B)flying in the same direction.
C)flying in different directions.
D)very tired and coming down to rest.

Question 72

A 1-N-falling apple hits the ground with a force of

A)1 N.
B)2 N.
C)4 N.
D)10 N.
E)not enough information

Question 73

A 5-kg fish swimming at 1 m/s swallows an absent-minded 1-kg fish swimming toward it at 4 m/s.The speed of the larger fish after lunch is

A)1/2 m/s.
B)1/5 m/s.
C)1/6 m/s.
D)2/3 m/s.
E)3/2 m/s.

Question 74

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard,he doesn't slip off the skateboard because of

A)inertia in motion.
B)momentum change.
C)friction between his feet and the board.

Question 75

An open freight car rolls friction-free along a horizontal track in vertically pouring rain.As water accumulates in the car,its speed

A)increases.
B)decreases.
C)doesn't change.

Question 76

Recoil is noticeable if we throw a heavy ball while standing on a skateboard.If instead we go through the throwing motion but hold onto the ball,without friction effects our net recoil will be

A)zero.
B)the same as before.
C)small,but noticeable.

Question 77

A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest.The speed of the larger fish after lunch is

A)1/2 m/s.
B)2/5 m/s.
C)5/6 m/s.
D)6/5 m/s.
E)1 m/s.

Question 78

A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track.When they collide and stick,the combined-glider speed is

A)0 m/s.
B)1/2 m/s.
C)1/3 m/s.
D)1/6 m/s.
E)1.5 m/s.

Question 79

A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball initially at rest.After the putty sticks to the ball,both move with a combined momentum of

A)less than 1 unit.
B)more than 1 unit.
C)1 unit.
D)not enough information

Question 80

A 1-kg chunk of putty moving at 1 m/s collides and sticks to a 5-kg bowling ball that is initially at rest in space.The bowling ball and putty are then set in motion with a speed of

A)1/4 m/s.
B)1/5 m/s.
C)1/6 m/s.
D)none of the above
E)not enough information