Question 1

The graph in the figure shows the  x  component  F  of the net force that acts for  10 s on a  100-kg crate. What is the change in the momentum of the crate during the  10 s that this force acts?

Accepted Answer

A)  $25 \mathrm {~kg} \cdot \mathrm { m } / \mathrm { s }$ 
B)  $- 75 \mathrm {~kg} \cdot \mathrm { m } / \mathrm { s }$ 
C)  $- 100 \mathrm {~kg} \cdot \mathrm { m } / \mathrm { s }$ 
D)  $75 \mathrm {~kg} \cdot \mathrm { m } / \mathrm { s }$ 
E)  $- 25 \mathrm {~kg} \cdot \mathrm { m } / \mathrm { s }$

Question 2

A fire hose is turned on the door of a burning building in order to knock the door down. This requires a force of 1000 N. If the hose delivers 40 kg of water per second, what is the minimum
Velocity of the stream needed to knock down the door, assuming the water doesn't bounce back?

Accepted Answer

A)  20 m/s 
B)  30 m/s 
C)  25 m/s 
D)  15 m/s

Question 3

In a police ballistics test, a 10.0-g bullet moving at  300 m/s  is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with  50.0%  of its original speed. What is the speed of the block just after the bullet emerges?

Accepted Answer

A)   1.50 m/s 
B)   273 m/s 
C)   3.00 m/s 
D)   2.97 m/s

Question 4

The center of mass (or center of gravity) of a two-particle system is at the origin. One particle is located at (3.0 m, 0.0 m) and has a mass of 2.0 kg. The other particle has a mass of 3.0 kg. What is
The location of the 3.0-kg particle?

Accepted Answer

A)  (3.0 m, 0.0 m) 
B)  (-2.0 m, 0.0 m) 
C)  (2.0 m, 0.0 m) 
D)  (-3.0 m, 0.0 m)

Question 5

A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. As a result of this bounce, which of the following quantities of the ball are
Conserved? (There could be more than one correct choice.)

Accepted Answer

A)  both the momentum and the kinetic energy of the ball 
B)  the momentum of the ball 
C)  the kinetic energy of the ball 
D)  None of the above quantities are conserved.

Question 6

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

Accepted Answer

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

Question 7

A 2200-kg auto moving northward at 12.0 m/s runs into a 3800-kg truck which is also
moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving
just after the collision?

Accepted Answer

The answer of A 2200-kg auto moving northward at 12.0...

Question 8

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average force during the collision is correct?

Accepted Answer

A)  The small car and the truck experience the same average force. 
B)  The small car experiences the greater average force. 
C)  The force experienced by each one is directly proportional to its mass. 
D)  The truck experiences the greater average force. 
E)  The force experienced by each one is inversely proportional to its mass.

Question 9

A  0.140 kg baseball is thrown horizontally with a velocity of  28.9 m/s. It is struck with a constant horizontal force that lasts for  1.85 ms, which results in a velocity of  37.0 m/s in the opposite direction. What was the magnitude of the horizontal force?

Accepted Answer

A)   4.99 kN 
B)   0.613 kN 
C)   2.80 kN 
D)   2.19 kN

Question 10

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

Accepted Answer

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

Question 11

A force of  5.3 N is needed to hold on to an umbrella in a strong wind. If the air molecules each have a mass of $4.7 \times 10 ^ { - 26 } \mathrm {~kg}$ and each one strikes the umbrella (without rebounding) with a speed of  2.0 m/s in the same direction, how many atoms strike the umbrella each second? Assume that the wind blows horizontally so that the gravity can be neglected.

Accepted Answer

The answer of A force of  5.3 N is...

Question 12

A puck with a mass $m _ { 1 } = 50 \mathrm {~g}$ moving at 1.0 m/s approaches a stationary puck with a mass $m _ { 2 } =$
 100 g on a frictionless air table, and they undergo a sudden two-dimensional elastic collision. After
the collision, both pucks have identical speeds, but travel in different directions. What is the angle
between the original and final paths of puck with mass $m _ { 1 } ?$

Accepted Answer

A)  $150 ^ { \circ }$ 
B)  $30 ^ { \circ }$ 
C)  $90 ^ { \circ }$ 
D)  $60 ^ { \circ }$ 
E)  $120 ^ { \circ }$

Question 13

A block of mass m = 9.0 kg and speed V and is behind a block of mass M = 27 kg and speed of 0.50 m/s, as shown int the figure. The surface is frictionless, and the blocks suddenly collide and
Couple. After the collision, the blocks have a common speed of 0.90 m/s. How much kinetic energy
Of the blocks is lost due to the collision?

Accepted Answer

A)   31 J 
B)   2.0 J 
C)   8.6 J 
D)   4.6 J 
E)   11 J

Question 14

Find the magnitude and direction of the net momentum of the system shown in the figure. Express the direction by giving the angle the net momentum makes with the  +x -axis.

Accepted Answer

The answer of Find the magnitude and direction of the...

Question 15

A proton of mass  m  is at rest when it is suddenly struck head-on by an alpha particle (which consists of 2 protons and 2 neutrons) moving at speed $\vec{U}^{j}$ If the collision is perfectly elastic, wha speed will the alpha particle have after the collision? (Assume the neutron's mass is equal to th proton's mass.)

Accepted Answer

A)  zero 
B)   3v/5 
C)  $2 v / 3$ 
D)  $5 v / 3$

Question 16

In the figure showing an isolated system, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is

Accepted Answer

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

Question 17

In a collision between two unequal masses, which mass receives a greater magnitude impulse?

Accepted Answer

A)  the smaller mass 
B)  the larger mass 
C)  They receive equal impulses.

Question 18

A 30-kg child stands at one end of a floating 20-kg canoe that is 5.0-m long and initially at rest in the water. The child then slowly walks to the other end of the canoe. How far does the canoe move
In the water, assuming water friction is negligible?

Accepted Answer

A)  4.0 m 
B)  3.0 m 
C)  2.0 m 
D)  1.0 m 
E)  5.0 m

Question 19

In a police ballistics test,  2.00-g bullet traveling at  700 m/s suddenly hits and becomes embedded in a stationary  5.00-kg wood block. What is the speed of the block immediately after the bullet has stopped moving relative to the block?

Accepted Answer

The answer of In a police ballistics test,  2.00-g...

Question 20

On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to the table. The puck compresses the spring by 15 cm before coming to rest. During the compression
Process, which quantities are conserved?

Accepted Answer

A)  only the momentum of the puck 
B)  the momentum and the mechanical energy of the puck 
C)  only the kinetic energy of the puck 
D)  the momentum and the kinetic energy of the puck 
E)  only the mechanical energy (kinetic plus potential) of the puck

Exam 7: Linear Momentum

The graph in the figure shows the x component F of the net force that acts for 10 s on a 100-kg crate. What is the change in the momentum of the crate during the 10 s that this force acts?

A fire hose is turned on the door of a burning building in order to knock the door down. This requires a force of 1000 N. If the hose delivers 40 kg of water per second, what is the minimum Velocity of the stream needed to knock down the door, assuming the water doesn't bounce back?

In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges?

The center of mass (or center of gravity) of a two-particle system is at the origin. One particle is located at (3.0 m, 0.0 m) and has a mass of 2.0 kg. The other particle has a mass of 3.0 kg. What is The location of the 3.0-kg particle?

A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. As a result of this bounce, which of the following quantities of the ball are Conserved? (There could be more than one correct choice.)

A 1200-kg car moving at 15.6 m/s suddenly 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 2200-kg auto moving northward at 12.0 m/s runs into a 3800-kg truck which is also moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving just after the collision?

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average force during the collision is correct?

A 0.140 kg baseball is thrown horizontally with a velocity of 28.9 m/s. It is struck with a constant horizontal force that lasts for 1.85 ms, which results in a velocity of 37.0 m/s in the opposite direction. What was the magnitude of the horizontal force?

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

Find the magnitude and direction of the net momentum of the system shown in the figure. Express the direction by giving the angle the net momentum makes with the +x -axis.

In the figure showing an isolated system, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is

In a collision between two unequal masses, which mass receives a greater magnitude impulse?

A 30-kg child stands at one end of a floating 20-kg canoe that is 5.0-m long and initially at rest in the water. The child then slowly walks to the other end of the canoe. How far does the canoe move In the water, assuming water friction is negligible?

In a police ballistics test, 2.00-g bullet traveling at 700 m/s suddenly hits and becomes embedded in a stationary 5.00-kg wood block. What is the speed of the block immediately after the bullet has stopped moving relative to the block?

On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to the table. The puck compresses the spring by 15 cm before coming to rest. During the compression Process, which quantities are conserved?