Deck 7: Linear Momentum

Question 1

The units of momentum are

A) $\mathrm{L} / \mathrm{T}^{2}$ .
B) $\mathrm{ML}^{2} / \mathrm{T}^{2}$ .
C) $M L / T$ .
D) $\mathrm{ML} / \mathrm{T}^{2}$ .
E) $\mathrm{M} / \mathrm{T}$ .

Answer 1

$M L / T$ .

Question 2

A $2.0 \mathrm{~kg}$ ball is moving at $4.0 \mathrm{~m} / \mathrm{s}$ WEST. The momentum of the ball is

A) $10 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ WEST.
B) $6.00 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ WEST.
C) $8.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ WEST.
D) $12 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ WEST.
E) $4.00 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ WEST.

Answer 2

$8.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ WEST.

Question 3

A $1,800 \mathrm{~kg}$ car is traveling at $20.0 \mathrm{~m} / \mathrm{s}$ NORTHEAST. The momentum of the car is

A) $20,000 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ NORTHEAST.
B) $36,000 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ NORTHEAST.
C) $28,000 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ NORTHEAST.
D) $18,000 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ NORTHEAST.
E) $32,000 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ NORTHEAST.

Answer 3

$36,000 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ NORTHEAST.

Question 4

A $30.00 \mathrm{~kg}$ mass falls from a height of $2.000 \mathrm{~m}$ . The magnitude of the momentum of the mass just before it hits the ground is

A) $320.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
B) $442.4 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
C) $187.8 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
D) $502.1 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
E) $144.2 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .

Question 5

A $3.000 \mathrm{~kg}$ ball is pitched with a kinetic energy of $20.00 \mathrm{~J}$ . The magnitude of the momentum of the ball is

A) $10.95 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
B) $8.350 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
C) $12.50 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
D) $9.450 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .
E) $7.500 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .

Question 6

A $4.0 \mathrm{~kg}$ ball is traveling at $5.0 \mathrm{~m} / \mathrm{s}$ to the right and strikes a wall. The ball bounces off the wall with a velocity of $4.0 \mathrm{~m} / \mathrm{s}$ to the left. The change in momentum of the ball is

A) $4.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ left.
B) $26 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ left.
C) $36 \mathrm{~kg} \mathrm{~m} / \mathrm{s} \mathrm{right.}$
D) $36 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ left.
E) $30 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ right.

Question 7

An $1800 \mathrm{~kg}$ car traveling at $35.0 \mathrm{~m} / \mathrm{s}$ strikes a wall. If the car comes to rest in 0.500 seconds, then the magnitude of the average force of the wall on the car is

A) $3.33 \times 10^{5} \mathrm{~N}$ .
B) $1.26 \times 10^{5} \mathrm{~N}$ .
C) $0.640 \times 10^{5} \mathrm{~N}$ .
D) $0.330 \times 10^{5} \mathrm{~N}$ .
E) $2.77 \times 10^{5} \mathrm{~N}$ .

Question 8

A $140 \mathrm{~g}$ baseball with a velocity of $25.0 \mathrm{~m} / \mathrm{s}$ is hit by a baseball bat and leaves at $30.0 \mathrm{~m} / \mathrm{s}$ in the opposite direction. If the ball was in contact with the bat for $12.0 \mathrm{~ms}$ , what was the average force on the ball?

A) $482 \mathrm{~N}$
B) $366 \mathrm{~N}$
C) $642 \mathrm{~N}$
D) $550 \mathrm{~N}$
E) $750 \mathrm{~N}$

Question 9

Two objects of equal mass and velocity hit a wall. They both rebound with the same velocity in the opposite direction. Both objects experience the same momentum change but one experiences twice the average force as the other. Which of the following statements is true?

A) The change in the kinetic energy is different for the two objects.
B) The contact time between one of the object and the wall is one-fourth the contact time of the other.
C) The contact time between one of the objects and the wall is $1 / 3$ the contact time of the other.
D) The contact times between the objects and the wall are equal.
E) The contact time between one of the objects and the wall is twice the contact time of the other.

Question 10

A $1200 \mathrm{~kg}$ car is traveling at $3.0 \mathrm{~m} / \mathrm{s}$ and strikes a wall. The car bounces off the wall with a velocity of 4.0 $\mathrm{m} / \mathrm{s}$ in the opposite direction. If the car is in contact with the wall for 0.10 seconds, then the magnitude of the average force of the wall on the car is

A) $75,000 \mathrm{~N}$ .
B) $55,000 \mathrm{~N}$ .
C) $84,000 \mathrm{~N}$ .
D) $46,000 \mathrm{~N}$ .
E) $63,000 \mathrm{~N}$ .

Question 11

A $3.0 \mathrm{~kg}$ object is moving to the right at $4.0 \mathrm{~m} / \mathrm{s}$ . It collides in a perfectly inelastic collision with a $6.0 \mathrm{~kg}$ object moving to the left at $2.0 \mathrm{~m} / \mathrm{s}$ . What is the total kinetic energy after the collision?

A) $0.0 \mathrm{~J}$
B) $12 \mathrm{~J}$
C) $62 \mathrm{~J}$
D) $25 \mathrm{~J}$

Question 12

A $5.00 \mathrm{~kg}$ ball is moving at $4.0 \mathrm{~m} / \mathrm{s}$ to the right and a $6.00 \mathrm{~kg}$ ball is moving at $3.00 \mathrm{~m} / \mathrm{s}$ to the left. The total momentum of the system is

A) $20 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the right.
B) $18 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the left.
C) $2.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the left.
D) $2.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the right.
E) $38 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the right.

Question 13

A $4.00 \mathrm{~kg}$ ball is moving at $4.0 \mathrm{~m} / \mathrm{s}$ to the right and a $6.00 \mathrm{~kg}$ ball is moving at $3.00 \mathrm{~m} / \mathrm{s}$ to the left. The total momentum of the system is

A) $34 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the left.
B) $16 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the right.
C) $2.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the right.
D) $2.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the left.
E) $18 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ to the left.

Question 14

A $4.00 \mathrm{~kg}$ ball is moving at $4.00 \mathrm{~m} / \mathrm{s}$ to the EAST and a $6.00 \mathrm{~kg}$ ball is moving at $3.00 \mathrm{~m} / \mathrm{s}$ to the NORTH. The total momentum of the system is

A) $24.1 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 48.4 degrees NORTH of EAST.
B) $24.1 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 24.2 degrees SOUTH of EAST.
C) $14.2 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 48.4 degrees SOUTH of EAST.
D) $48.2 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 24.2 degrees SOUTH of EAST.
E) $48.2 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 48.4 degrees NORTH of EAST.

Question 15

A $4.00 \mathrm{~kg}$ ball is moving at $2.00 \mathrm{~m} / \mathrm{s}$ to the WEST and a $6.00 \mathrm{~kg}$ ball is moving at $2.00 \mathrm{~m} / \mathrm{s}$ to the NORTH. The total momentum of the system is

A) $21.6 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 17.7 degrees NORTH of WEST.
B) $21.6 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 56.3 degrees NORTH of WEST.
C) $21.6 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 45.2 degrees SOUTH of WEST.
D) $14.4 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 45.2 degrees SOUTH of WEST.
E) $14.4 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 56.3 degrees NORTH of WEST.

Question 16

A $4.00 \mathrm{~kg}$ ball is moving at $2.00 \mathrm{~m} / \mathrm{s}$ to the SOUTH and a $6.00 \mathrm{~kg}$ ball is moving at $2.00 \mathrm{~m} / \mathrm{s}$ to the NORTHWEST. The total momentum of the system is

A) $15.8 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 17.2 degrees NORTH of WEST.
B) $15.8 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 3.27 degrees NORTH of WEST.
C) $8.5 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 3.27 degrees NORTH of WEST.
D) $20.1 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 27.5 degrees NORTH of WEST.
E) $8.5 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 17.2 degrees NORTH of WEST.

Question 17

A $4.00 \mathrm{~kg}$ ball is moving at $3.00 \mathrm{~m} / \mathrm{s}$ to the NORTH and a $5.00 \mathrm{~kg}$ ball is moving at $2.00 \mathrm{~m} / \mathrm{s}$ to the NORTHEAST. The total momentum of the system is

A) $43.00 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 45.0 degrees NORTH of EAST.
B) $26.1 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 69.7 degrees SOUTH of EAST.
C) $20.3 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 24.6 degrees SOUTH of EAST.
D) $26.1 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 24.6 degrees NORTH of EAST.
E) $20.3 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at an angle of 69.7 degrees NORTH of EAST.

Question 18

A $3.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=2.0 \mathrm{~cm}$ and $\mathrm{y}=4.0 \mathrm{~cm}$ . A $3.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=-5.0 \mathrm{~cm}$ and $\mathrm{y}=$ $2.0 \mathrm{~cm}$ . A $4.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=3.0 \mathrm{~cm}$ and $\mathrm{y}=-3.0 \mathrm{~cm}$ . Where is the center of mass $(\mathrm{x}, \mathrm{y})$ ?

A) $(3.9 \mathrm{~cm}, 3.0 \mathrm{~cm})$
B) $(0.60 \mathrm{~cm}, 0.30 \mathrm{~cm})$
C) $(3.0 \mathrm{~cm}, 1.0 \mathrm{~cm})$
D) $(0.30 \mathrm{~cm}, 0.60 \mathrm{~cm})$
E) $(0.90 \mathrm{~cm}, 2.0 \mathrm{~cm})$

Question 19

A $3.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=2.0 \mathrm{~cm}$ and $\mathrm{y}=-4.0 \mathrm{~cm}$ . A $3.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=-5.0 \mathrm{~cm}$ and $\mathrm{y}=$ $2.0 \mathrm{~cm}$ . A $4.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=-3.0 \mathrm{~cm}$ and $\mathrm{y}=-3.0 \mathrm{~cm}$ . Where is the center of mass $(\mathrm{x}, \mathrm{y})$ ?

A) $(+2.1 \mathrm{~cm},-1.8 \mathrm{~cm})$
B) $(-0.10 \mathrm{~cm},-0.50 \mathrm{~cm})$
C) $(-2.1 \mathrm{~cm},-1.8 \mathrm{~cm})$
D) $(+1.1 \mathrm{~cm},-2.0 \mathrm{~cm})$
E) $(-2.1 \mathrm{~cm},+1.8 \mathrm{~cm})$

Question 20

A $30.0 \mathrm{~g}$ mass is located at the origin. Where must a mass of $10.0 \mathrm{~g}$ be located if the coordinates of the center of mass are $(0.00 \mathrm{~cm}, 10.0 \mathrm{~cm})$ ?

A) $(0.00 \mathrm{~cm}, 5.00 \mathrm{~cm})$
B) $(0.00 \mathrm{~cm}, 40.0 \mathrm{~cm})$
C) $(0.00 \mathrm{~cm}, 20.0 \mathrm{~cm})$
D) $(0.00 \mathrm{~cm}, 10.0 \mathrm{~cm})$
E) $(0.00 \mathrm{~cm}, 7.50 \mathrm{~cm})$

Question 21

A $3.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=2.0 \mathrm{~cm}$ and $\mathrm{y}=0.0 \mathrm{~cm}$ . A $3.00 \mathrm{~kg}$ mass is located at $\mathrm{x}=0.0 \mathrm{~cm}$ and $\mathrm{y}=$ $2.0 \mathrm{~cm}$ . A $4.00 \mathrm{~kg}$ mass is located at $x=3.0 \mathrm{~cm}$ and $y=-3.0 \mathrm{~cm}$ . Where is the location of the center of mass?

A) $(3.5 \mathrm{~cm},-0.6 \mathrm{~cm})$
B) $(0.60 \mathrm{~cm},-1.8 \mathrm{~cm})$
C) $(1.8 \mathrm{~cm}, 0.60 \mathrm{~cm})$
D) $(1.8 \mathrm{~cm},-0.60 \mathrm{~cm})$
E) $(1.8 \mathrm{~cm}, 1.6 \mathrm{~cm})$

Question 22

A $4.00 \mathrm{~kg}$ mass is moving at $4.00 \mathrm{~m} / \mathrm{s} 45.0$ degrees NORTH of WEST and a $6.00 \mathrm{~kg}$ mass is moving at $3.00 \mathrm{~m} / \mathrm{s} 30.0$ degrees SOUTH of EAST. Find the velocity of the center of mass, letting (a) = the east-west component, and $(\mathrm{b})=$ the north-south component.

A) $\mathrm{a}=0.427 \mathrm{~m} / \mathrm{s}, \mathrm{b}=0.213 \mathrm{~m} / \mathrm{s}$ .
B) $\mathrm{a}=0.427 \mathrm{~m} / \mathrm{s}, \mathrm{b}=2.31 \mathrm{~m} / \mathrm{s}$ .
C) $\mathrm{a}=1.23 \mathrm{~m} / \mathrm{s}, \mathrm{b}=0.231 \mathrm{~m} / \mathrm{s}$ .
D) $\mathrm{a}=1.73 \mathrm{~m} / \mathrm{s}, \mathrm{b}=1.43 \mathrm{~m} / \mathrm{s}$ .
E) $\mathrm{a}=0.427 \mathrm{~m} / \mathrm{s}, \mathrm{b}=0.231 \mathrm{~m} / \mathrm{s}$ .

Question 23

A $5.00 \mathrm{~kg}$ mass is moving at $4.00 \mathrm{~m} / \mathrm{s} 30.0$ degrees SOUTH of WEST and a $2.00 \mathrm{~kg}$ mass is moving at 3.00 $\mathrm{m} / \mathrm{s} 60.0$ degrees SOUTH of EAST. Find the velocity of the center of mass, letting $(\mathrm{a})=$ the east-west component, and (b) = the north-south component.

A) $\mathrm{a}=-2.17 \mathrm{~m} / \mathrm{s}, \mathrm{b}=+2.05 \mathrm{~m} / \mathrm{s}$ .
B) $\mathrm{a}=+2.17 \mathrm{~m} / \mathrm{s}, \mathrm{b}=-2.05 \mathrm{~m} / \mathrm{s}$ .
C) $\mathrm{a}=-2.05 \mathrm{~m} / \mathrm{s}, \mathrm{b}=-2.17 \mathrm{~m} / \mathrm{s}$ .
D) $\mathrm{a}=-2.05 \mathrm{~m} / \mathrm{s}, \mathrm{b}=+2.17 \mathrm{~m} / \mathrm{s}$ .
E) $\mathrm{a}=+2.05 \mathrm{~m} / \mathrm{s}, \mathrm{b}=-2.17 \mathrm{~m} / \mathrm{s}$ .

Question 24

A $8.00 \mathrm{~kg}$ mass is moving at $5.00 \mathrm{~m} / \mathrm{s}$ SOUTH and a $6.00 \mathrm{~kg}$ mass is moving at $7.00 \mathrm{~m} / \mathrm{s}$ EAST. Find the velocity of the center of mass, letting (a) = the east-west component, and $(\mathrm{b})=$ the north-south component.

A) $\mathrm{a}=+0.50 \mathrm{~m} / \mathrm{s}, \mathrm{b}=+3.00 \mathrm{~m} / \mathrm{s}$ .
B) $\mathrm{a}=+42.0 \mathrm{~m} / \mathrm{s}, \mathrm{b}=-40.0 \mathrm{~m} / \mathrm{s}$ .
C) $\mathrm{a}=-3.00 \mathrm{~m} / \mathrm{s}, \mathrm{b}=-3.00 \mathrm{~m} / \mathrm{s}$ .
D) $\mathrm{a}=+3.00 \mathrm{~m} / \mathrm{s}, \mathrm{b}=+2.86 \mathrm{~m} / \mathrm{s}$ .
E) $\mathrm{a}=+3.00 \mathrm{~m} / \mathrm{s}, \mathrm{b}=-2.86 \mathrm{~m} / \mathrm{s}$ .

Question 25

A $10 \mathrm{~kg}$ bomb is moving NORTH with a velocity of $4.0 \mathrm{~m} / \mathrm{s}$ . It explodes into three fragments: a $5.0 \mathrm{~kg}$ fragment moving WEST with a speed of $8.0 \mathrm{~m} / \mathrm{s}$ , a $4.0 \mathrm{~kg}$ fragment moving EAST with a speed of $10 \mathrm{~m} / \mathrm{s}$ , and a third $1.0 \mathrm{~kg}$ fragment. What is the velocity of the third fragment?

A) $40 \mathrm{~m} / \mathrm{s} \mathrm{NORTH}$
B) $40 \mathrm{~m} / \mathrm{s}$ SOUTH
C) zero
D) none of these answers are correct

Question 26

If a $5.00 \mathrm{~kg}$ mass is moving EAST at $10.0 \mathrm{~m} / \mathrm{s}$ and a $15.0 \mathrm{~kg}$ mass is moving WEST at $10 \mathrm{~m} / \mathrm{s}$ , what is the velocity of the center of mass of the pair?

A) $5.0 \mathrm{~m} / \mathrm{s} \mathrm{EAST}$
B) $5.0 \mathrm{~m} / \mathrm{s} \mathrm{WEST}$
C) $10 \mathrm{~m} / \mathrm{s}$ EAST
D) $10 \mathrm{~m} / \mathrm{s}$ WEST

Question 27

A rocket of length $80 \mathrm{~m}$ sits on a launch pad in outer space. The center of mass of the combined rocket and launch pad system is located in the center of the launch pad. The rocket is launched and reaches a distance of $100,000 \mathrm{~km}$ from the starting position. Where is the location of the center of mass of the total rocket-fuel-launch pad system then?

A) at the center of the launch pad
B) at the starting position
C) 50,000 km from the launch pad
D) $100,000 \mathrm{~km}$ from the launch pad
E) $80 \mathrm{~m}$ from the launch pad

Question 28

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ WEST. It catches up to and strikes a $6.00 \mathrm{~kg}$ that is moving WEST at $2.00 \mathrm{~m} / \mathrm{s}$ . The objects undergo an elastic collision and move away in the EAST-WEST direction. The velocity of the $6.00 \mathrm{~kg}$ object after the collision is

A) $1.40 \mathrm{~m} / \mathrm{s}$ EAST.
B) $1.40 \mathrm{~m} / \mathrm{s}$ WEST.
C) $3.00 \mathrm{~m} / \mathrm{s}$ WEST.
D) $4.40 \mathrm{~m} / \mathrm{s}$ WEST.
E) $4.40 \mathrm{~m} / \mathrm{s}$ EAST.

Question 29

A $4.00 \mathrm{~kg}$ object is moving at $3.00 \mathrm{~m} / \mathrm{s}$ WEST. It catches up to and strikes a $6.00 \mathrm{~kg}$ that is moving WEST at $2.00 \mathrm{~m} / \mathrm{s}$ . The objects undergo an elastic collision in the EAST-WEST direction. The velocity of the 4.00 $\mathrm{kg}$ object after the collision is

A) $1.80 \mathrm{~m} / \mathrm{s}$ EAST.
B) $1.80 \mathrm{~m} / \mathrm{s}$ WEST.
C) $1.00 \mathrm{~m} / \mathrm{s}$ WEST.
D) $2.80 \mathrm{~m} / \mathrm{s}$ WEST.
E) $2.80 \mathrm{~m} / \mathrm{s}$ EAST.

Question 30

A $3.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ EAST. It catches up to and strikes a $6.00 \mathrm{~kg}$ that is moving EAST at $2.00 \mathrm{~m} / \mathrm{s}$ . The objects undergo an elastic collision in the EAST-WEST direction. The velocity of the $3.00 \mathrm{~kg}$ object after the collision is

A) $4.00 \mathrm{~m} / \mathrm{s}$ EAST.
B) $3.00 \mathrm{~m} / \mathrm{s}$ EAST.
C) $1.00 \mathrm{~m} / \mathrm{s}$ EAST.
D) $1.00 \mathrm{~m} / \mathrm{s}$ WEST.
E) $4.00 \mathrm{~m} / \mathrm{s}$ WEST.

Question 31

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ EAST. It strikes a $5.00 \mathrm{~kg}$ that is moving WEST at $2.00 \mathrm{~m} / \mathrm{s}$ . The objects collide elastically and move away in the EAST-WEST direction. The velocity of the $5.00 \mathrm{~kg}$ object after the collision is

A) $2.78 \mathrm{~m} / \mathrm{s}$ EAST.
B) $4.22 \mathrm{~m} / \mathrm{s}$ EAST.
C) $1.11 \mathrm{~m} / \mathrm{s}$ WEST.
D) $4.22 \mathrm{~m} / \mathrm{s}$ WEST.
E) $2.78 \mathrm{~m} / \mathrm{s}$ WEST.

Question 32

A ball collides with a second ball at rest. As a result of the collision, the first ball comes to rest and the second ball moves off at the speed of the first ball. In this collision

A) the masses are equal and total kinetic energy is not conserved.
B) the masses are unequal and total kinetic energy is conserved.
C) the masses are equal and total kinetic energy is conserved.
D) the masses are unequal and total kinetic energy is not conserved.
E) not enough information to say whether masses are equal or total kinetic energy is conserved.

Question 33

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ NORTH. It strikes a $6.00 \mathrm{~kg}$ object that is moving WEST at 2.00 $\mathrm{m} / \mathrm{s}$ . The objects undergo a perfectly inelastic collision (stick together). The velocity of the $4.00 \mathrm{~kg}$ object after the collision is

A) $1.93 \mathrm{~m} / \mathrm{s}$ at an angle of 45.0 degrees NORTH of WEST.
B) $1.93 \mathrm{~m} / \mathrm{s}$ at an angle of 59.0 degrees NORTH of WEST.
C) $2.54 \mathrm{~m} / \mathrm{s}$ at an angle of 35.0 degrees NORTH of WEST.
D) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 45.0 degrees NORTH of WEST.
E) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 59.0 degrees NORTH of WEST.

Question 34

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ NORTH. It strikes a $6.00 \mathrm{~kg}$ object that is moving EAST at 2.00 $\mathrm{m} / \mathrm{s}$ . The objects undergo a perfectly inelastic (stick together) collision. The velocity of the $6.00 \mathrm{~kg}$ object after the collision is

A) $2.00 \mathrm{~m} / \mathrm{s}$ at an angle of 59.0 degrees NORTH of EAST.
B) $2.00 \mathrm{~m} / \mathrm{s}$ at an angle of 45.0 degrees NORTH of EAST.
C) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 59.0 degrees NORTH of EAST.
D) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 35.0 degrees NORTH of EAST.
E) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 45.0 degrees NORTH of EAST.

Question 35

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ NORTHWEST. It strikes a $6.00 \mathrm{~kg}$ object that is moving SOUTHWEST at $2.00 \mathrm{~m} / \mathrm{s}$ . The objects collide perfectly inelastically (stick together). The velocity of the $6.00 \mathrm{~kg}$ object after the collision is

A) $3.89 \mathrm{~m} / \mathrm{s}$ at an angle of 35.0 degrees NORTH of WEST.
B) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 35.0 degrees NORTH of WEST.
C) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 45.0 degrees NORTH of WEST.
D) $3.89 \mathrm{~m} / \mathrm{s}$ at an angle of 14.0 degrees NORTH of WEST.
E) $2.33 \mathrm{~m} / \mathrm{s}$ at an angle of 14.0 degrees NORTH of WEST.

Question 36

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ EAST. It strikes a $6.00 \mathrm{~kg}$ object that is at rest. The objects undergo an elastic collision. The velocity of the $4.00 \mathrm{~kg}$ object after the collision is at an angle of 30.0 degrees SOUTH of EAST. The speed of the $4.00 \mathrm{~kg}$ mass after the collision is

A) $3.55 \mathrm{~m} / \mathrm{s}$ .
B) $1.67 \mathrm{~m} / \mathrm{s}$ .
C) $4.56 \mathrm{~m} / \mathrm{s}$ .
D) $2.66 \mathrm{~m} / \mathrm{s}$ .
E) $5.78 \mathrm{~m} / \mathrm{s}$ .

Question 37

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ EAST. It strikes a $6.00 \mathrm{~kg}$ object that is at rest. The objects collide elastically. The velocity of $4.00 \mathrm{~kg}$ object after the collision is in the SOUTHWEST direction. The speed of the $6.00 \mathrm{~kg}$ object after the collision is

A) $3.02 \mathrm{~m} / \mathrm{s}$ .
B) $3.96 \mathrm{~m} / \mathrm{s}$ .
C) $2.38 \mathrm{~m} / \mathrm{s}$ .
D) $4.06 \mathrm{~m} / \mathrm{s}$ .
E) $5.22 \mathrm{~m} / \mathrm{s}$ .

Question 38

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ NORTH. It strikes a $6.00 \mathrm{~kg}$ object that is moving WEST at 2.00 $\mathrm{m} / \mathrm{s}$ . The objects undergo a perfectly inelastic (stick together) collision. The kinetic energy lost in the collision is

A) $28.7 \mathrm{~J}$ .
B) $34.8 \mathrm{~J}$ .
C) $14.9 \mathrm{~J}$ .
D) $20.4 \mathrm{~J}$ .
E) $18.7 \mathrm{~J}$ .

Question 39

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ NORTHWEST. It strikes a $6.00 \mathrm{~kg}$ object that is moving SOUTHWEST at $2.00 \mathrm{~m} / \mathrm{s}$ . The collision is perfectly inelastic. The kinetic energy lost in the collision is

A) $45.1 \mathrm{~J}$ .
B) $34.8 \mathrm{~J}$ .
C) $20.4 \mathrm{~J}$ .
D) $40.2 \mathrm{~J}$ .
E) $28.7 \mathrm{~J}$ .

Question 40

A $4.00 \mathrm{~kg}$ object is moving at $5.00 \mathrm{~m} / \mathrm{s}$ SOUTH. It strikes a $3.00 \mathrm{~kg}$ object that is moving WEST at 2.00 $\mathrm{m} / \mathrm{s}$ . The collision is perfectly inelastic. The kinetic energy lost in the collision is

A) $10.5 \mathrm{~J}$ .
B) $24.9 \mathrm{~J}$ .
C) $2.61 \mathrm{~J}$ .
D) $8.33 \mathrm{~J}$ .
E) $18.4 \mathrm{~J}$ .

Question 41

A car accelerates from rest along a straight road, increasing its momentum from 0 to $52500 \mathrm{~kg} \cdot \mathrm{m} / \mathrm{s}$ in $6.5 \mathrm{~s}$ . If its engine and tires are able to provide an average force of $8500 \mathrm{~N}$ , what is the magnitude of the net dissipative force (friction and air resistance) on the car during this interval?

A) $3510 \mathrm{~N}$
B) $11450 \mathrm{~N}$
C) $1840 \mathrm{~N}$
D) $423 \mathrm{~N}$

Question 42

An apple and an orange are connected by a straw of negligible mass. If the centers of the fruits are $26 \mathrm{~cm}$ apart and the center of mass of the pair is $11 \mathrm{~cm}$ from the apple, what is the ratio of $\mathrm{m}_{\text {apple }}$ to $\mathrm{m}_{\text {orange }}$ ?

A) $26 / 11$
B) $15 / 11$
C) $15 / 26$
D) $26 / 15$
E) $11 / 15$
F) $11 / 26$

Question 43

A binary star system is composed of two stars (one blue, one red) that orbit a common center of mass. Let the distances from the stars to the center of mass be labeled $\mathrm{r}_{\mathrm{blue}}$ and $\mathrm{r}_{\text {red. }}$ . The sum of the masses of the stars is $\mathrm{M}_{\mathrm{blue}}+\mathrm{M}_{\mathrm{red}}=3.70 \times 1033 \mathrm{~kg}$ . If it is known that $\mathrm{r}_{\mathrm{blue}}=2 / 5 \mathrm{r}_{\mathrm{red}}$ , what is $\mathrm{M}_{\mathrm{red}}$ ?

A) $2.64 \times 1033 \mathrm{~kg}$
B) $1.48 \times 1033 \mathrm{~kg}$
C) $2.22 \times 1033 \mathrm{~kg}$
D) $1.06 \times 10^{33} \mathrm{~kg}$

Question 44

A $250 \mathrm{~g}$ sticky hockey puck slides along a frictionless, horizontal ice surface at $75 \mathrm{~m} / \mathrm{s}$ in the $+\mathrm{x}$ direction. It collides with a $500 \mathrm{~g}$ sticky puck originally sliding at $25 \mathrm{~m} / \mathrm{s}$ in the -y direction. They collide perfectly inelastically. How much kinetic energy is lost in this collision?

A) $521 \mathrm{~J}$
B) $520 \mathrm{~J}$
C) $779 \mathrm{~J}$
D) More information is needed