Deck 9: Momentum

Question 1

A golf ball of mass 0.050 kg is at rest on the tee and has a velocity of 102 m/s immediately after being struck.If the club and ball were in contact for 0.81 ms,what is the average force exerted on the ball?

A)6.3 kN
B)7.1 kN
C)5.5 kN
D)4.9 kN

Answer 1

6.3 kN

Question 2

A child swings a 0.38 kg ball in a circle on a string that is 1.3 m long.If the ball makes 1.2 rev/s,what is the magnitude of the ball's angular momentum?

A)4.8 kg∙m²/s
B)0.8 kg∙m²/s
C)3.8 kg∙m²/s
D)5.3 kg∙m²/s

Answer 2

4.8 kg∙m²/s

Question 3

A block of mass m = 7.6 kg,moving on a frictionless surface with a speed v_i = 7.6 m/s,makes a perfectly elastic collision with a block of mass M at rest.After the collision,the 7.6 kg block recoils with a speed of v_f = 2.5 m/s.In the figure,the blocks are in contact for 0.20 s.The average force on the 7.6 kg block,while the two blocks are in contact,is closest to:

A)384 N
B)336 N
C)289 N
D)241 N
E)194 N

Answer 3

384 N

Question 4

Two vehicles approach a right angle intersection and then collide.After the collision,they become entangled.If their mass ratios were 1: 4 and their respective speeds as they approached were both 13 m/s,find the magnitude and direction of the final velocity of the wreck.

A)13.1 m/s at 79°
B)16.3 m/s at 79°
C)12.5 m/s at 79°
D)15.7 m/s at 79°

Question 5

A 480 kg car moving at 14.4 m/s hits from behind another car moving at 13.3 m/s in the same direction.If the second car has a mass of 570 kg and a new speed of 17.9 m/s,what is the velocity of the first car after the collision?

A)8.94 m/s
B)10.5 m/s
C)19.9 m/s
D)- 8.94 m/s

Question 6

A 1200 kg car moving at 15.6 m/s collides with a stationary car of mass 1500 kg If the two vehicles lock together,what is their combined velocity immediately after the collision?

A)6.9 m/s
B)8.6 m/s
C)12.1 m/s
D)5.5 m/s

Question 7

Calculate the impulse associated with a force of 4.5 N that lasts for 1.4 s.

A)6.3 kg∙ m/s
B)5.0 kg∙ m/s
C)5.7 kg∙ m/s
D)6.9 kg∙ m/s

Question 8

A 1200 kg cannon fires a 100.0 kg cannonball at 35 m/s.What is the recoil velocity of the cannon? Assume that frictional forces are negligible and the cannon is fired horizontally.

A)2.9 m/s
B)35 m/s
C)3.5 m/s
D)3.2 m/s

Question 9

A block of mass m = 2.2 kg,moving on frictionless surface with a speed v_i = 9.1 m/s,makes a perfectly elastic collision with a block of mass M at rest.After the collision,the 2.2 kg block recoils with a speed of v_f = 0.7 m/s.In the figure,the mass M is closest to:

A)2.6 kg
B)18.48 kg
C)2.4 kg
D)31 kg
E)2.2 kg

Question 10

A fisherman throws the anchor off her boat at an angle of 3.0° above the horizontal.If the anchor weighs 2.0 times as much as she does and the boat moves with speed 2.7 m/s during the launch,how fast did she throw the anchor? (Solve for her frame of reference.Assume the mass of the boat is negligible. )

A)4.1 m/s
B)1.4 m/s
C)4.0 m/s
D)1.3 m/s

Question 11

A 14 cm diameter champagne bottle rests on its side on top of a frictionless table.Suddenly,the cork pops and the bottle slides backward for a distance of 22.0 cm in 0.44 s.If the mass of the bottle is 500 times the mass of the cork,find the distance from the original position the cork will land on the table.

A)3000 cm
B)60 m
C)85 m
D)8.5 cm

Question 12

A 0.140 kg baseball is thrown with a velocity of 26.2 m/s.It is struck with an average force of 5000.0 N,which results in a velocity of 37.0 m/s in the opposite direction.How long were the bat and ball in contact?

A)1.77 × 10^-3 s
B)1.26 × 10^-2 s
C)3.02 × 10^-2 s
D)4.25 × 10^-3 s

Question 13

Three objects are moving along a straight line as shown in the figure.Taking the positive direction to be to the right,what is the total momentum of this system?

A)+106 kg m/s
B)-106 kg m/s
C)+14 kg m/s
D)-14 kg m/s
E)0 kg m/s

Question 14

A 0.24 kg blob of clay is thrown at a wall with an initial velocity of 23 m/s.If the clay comes to a stop in 91 ms,what is the average force experienced by the clay?

A)61 N
B)38 N
C)51 N
D)74 N

Question 15

A block of mass m = 3.6 kg,moving on a frictionless surface with a speed vi = 9.3 m/s,makes a perfectly elastic collision with a block of mass M at rest.After the collision,the 3.6 kg block recoils with a speed of v_f = 2.7 m/s.In the figure,the speed of the block of mass M after the collision is closest to:

A)6.6 m/s
B)8.0 m/s
C)9.3 m/s
D)10.7 m/s
E)12.0 m/s

Question 16

A 1120 kg car experiences an impulse of 30,000.0 N · s during a collision with a wall.If the collision takes 0.43 s,what was the velocity of the car just before the collision?

A)27 m/s
B)12 m/s
C)63 m/s
D)22 m/s

Question 17

A 1200 kg ore cart is rolling at 10.8 m/s across a flat surface.A crane dumps 691 kg of ore (vertically)into the cart.How fast does the cart move after being loaded with ore? Assume that frictional forces may be neglected.

A)6.8 m/s
B)4.1 m/s
C)4.6 m/s
D)6.2 m/s

Question 18

A steel ball is thrown in the air with a speed of 3.6 m/s at an angle of 70° from the horizontal.It drops on another steel ball of 1.4 times its mass resting on a sandy surface.If the original ball comes to a rest after the collision and the resting ball bounces,find the horizontal component of its velocity.

A)0.88 m/s
B)1.7 m/s
C)2.4 m/s
D)0.72 m/s

Question 19

A container explodes and breaks into three fragments that fly off 120° apart from each other,with mass ratios 1: 4: 2.If the first piece flies off with a speed of 6.0 m/s,what is the speed of the other two fragments? (All fragments are in the plane. )

A)1.5 and 3.0 m/s
B)0.9 and 3.0 m/s
C)1.5 and 0.9 m/s
D)1.0 and 3.0 m/s

Question 20

A car heading north collides at an intersection with a truck heading east.If they lock together and travel at 28 m/s at 46° north of east just after the collision,how fast was the car initially traveling? Assume that the two vehicles have the same mass.

A)40 m/s
B)20 m/s
C)80 m/s
D)30 m/s

Question 21

A girl of mass 55 kg throws a ball of mass 0.8 kg against a wall.The ball strikes the wall horizontally with a speed of 25 m/s,and it bounces back with this same speed.The ball is in contact with the wall 0.05 s.What is the average force exerted on the wall by the ball?

A)800 N
B)400 N
C)55,000 N
D)27,500 N
E)13,750 N

Question 22

Three solid,uniform flywheels,each of mass 65.0 kg and radius 1.47 m,rotate independently around a common axis.Two of the flywheels rotate in one direction at 3.83 rad/s;the other rotates in the opposite direction at 3.42 rad/s.Calculate the magnitude of the net angular momentum of the system.

A)298 kg∙ m²/s
B)778 kg∙ m²/s
C)257 kg∙ m²/s
D)222 kg∙ m²/s

Question 23

An 8 g bullet is shot into a 4.0 kg block,at rest on a frictionless horizontal surface.The bullet remains lodged in the block.The block moves into a spring and compresses it by 3.7 cm.The force constant of the spring is 2500 N/m.In the figure,the initial velocity of the bullet is closest to:

A)460 m/s
B)440 m/s
C)480 m/s
D)500 m/s
E)520 m/s

Question 24

In a collision between a small car and a large truck,the car and the truck undergo the same change in their velocities.

Question 25

A 1.4 kg object at x = 2.00 m,y = 3.10 m moves at 4.62 m/s at an angle 45° north of east.Calculate the magnitude of the object's angular momentum about the origin.

A)5.0 kg∙ m²/s
B)3.6 kg∙ m²/s
C)6.0 kg∙ m²/s
D)7.0 kg∙ m²/s

Question 26

You are standing on a skateboard,initially at rest.A friend throws a very heavy ball toward you.You can either catch the object or deflect the object back toward your friend (such that it moves away from you with the same speed as it was originally thrown).What should you do in order to maximize your speed on the skateboard?

A)catch the ball
B)deflect the ball back
C)Your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball.

Question 27

In the figure,determine the character of the collision.The masses of the blocks,and the velocities before and after are given.The collision is:

A)perfectly elastic.
B)partially inelastic.
C)completely inelastic.
D)characterized by an increase in kinetic energy.
E)not possible because momentum is not conserved.

Question 28

A uniform,solid flywheel of radius 1.4 m and mass 15 kg rotates at 2.4 rad/s.What is the magnitude of the flywheel's angular momentum?

A)35 kg∙m²/s
B)18 kg∙m²/s
C)70 kg∙m²/s
D)53 kg∙m²/s

Question 29

A rubber ball moving horizontally at 8.50 m/s hits a brick wall and bounces back with exactly the same speed but in the opposite direction.During this collision,its change in momentum is zero.

Question 30

A 51 g steel ball is released from rest and falls vertically onto a steel plate.The ball strikes the plate and is in contact with it for 0.5 ms.The ball rebounds elastically,and returns to its original height.The time interval for a round trip is 3.00 s.In this situation,the average force exerted on the ball during contact with the plate is closest to:

A)3000 N
B)1500 N
C)2490 N
D)2000 N
E)3500 N

Question 31

A car of mass 1411 kg collides head-on with a parked truck of mass 2000 kg.Spring mounted bumpers ensure that the collision is essentially elastic.If the velocity of the truck is 17 km/h (in the same direction as the car's initial velocity)after the collision,what is the initial speed of the car?

A)21 km/h
B)42 km/h
C)32 km/h
D)11 km/h

Question 32

In a ballistics test,a bullet traveling horizontally strikes and embeds itself in a large block that is free to move.During this process,the bullet transfers all of its momentum to the block.

Question 33

As a tile falls from the roof of a building to the ground its momentum is conserved.

Question 34

Three cars,Car X,Car Y,and Car Z,begin accelerating from rest,at the same time.Car X is more massive than Car Y,which is more massive than Car Z.The net force exerted on each car is identical.After 10 seconds,which car has the most amount of momentum?

A)They all have the same amount of momentum.
B)Car X
C)Car Y
D)Car Z

Question 35

In a collision between a light hydrogen molecule and a heavy water molecule,the momentum lost by one molecule is exactly the same as the momentum gained by the other molecule.

Question 36

Two ice skaters of identical mass approach on parallel paths 1.6 m apart.Both are moving at 3.0 m/s.They join hands as they pass,maintaining their 1.6 m separation,and begin rotating about each other.What is their angular speed?

A)3.7 rad/s
B)2.4 rad/s
C)3.0 rad/s
D)4.8 rad/s

Question 37

In the figure,determine the character of the collision.The masses of the blocks,and the velocities before and after are given.The collision is:

A)perfectly elastic.
B)partially inelastic.
C)completely inelastic.
D)not possible because momentum is not conserved.

Question 38

A shell explodes into two fragments,one 25 times heavier than the other.The momentum change of the lighter fragment is 25 times as great as the momentum change of the heavier fragment.

Question 39

When a baseball player hits a home run,the baseball receives a greater impulse from the bat than the bat does from the ball.

Question 40

A ball of clay is thrown against a wall and sticks there.In this process,momentum is not conserved because the clay stops moving.

Question 41

Two friends are standing on opposite ends of a canoe.The canoe is initially at rest with respect to the lake.The person on the right throws a very massive ball to the left,and the person on the left catches it.After the ball is caught (ignoring friction between the canoe and the water),the canoe is

A)stationary.
B)moving to the right.
C)moving to the left.

Question 42

During World War I,Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away.This gun also had a long barrel.What is the reason for using a long barrel in these guns?

A)to reduce frictional losses
B)to allow the force of the expanding gases from the gunpowder to act for a longer time
C)to increase the force exerted on the bullet due to the expanding gases from the gunpowder
D)to reduce the force exerted on the bullet due to the expanding gases from the gunpowder

Question 43

A 5 kg ball collides head-on with a 10 kg ball,which is initially stationary.The collision is inelastic.Which statement is true?

A)The magnitude of the change of velocity the 5 kg ball experiences is greater than that of the 10 kg ball.
B)The magnitude of the change of velocity the 5 kg ball experiences is less than that of the 10 kg ball.
C)The magnitude of the change of velocity the 5 kg ball experiences is equal to that of the 10 kg ball.
D)The magnitude of the change of the momentum of the 5 kg ball is equal to the magnitude of the change of momentum of the 10 kg ball.
E)Two of the above statements are true.