Question 1

An exam paper contains the following equation for rocket propulsion: e) , the velocity of the fuel relative to the ground should be A)  −ve. B)  +ve. C)  v − ve. D)  ve − v. E)  2ve." class="answers-bank-image d-inline" rel="preload" > . The error in the equation is that, instead of (v + ve) , the velocity of the fuel relative to the ground should be

Accepted Answer

A)   −ve.
B)   +ve.
C)   v − ve.
D)   ve − v.
E)   2ve.F) B) and D)
G) A) and E)

Question 2

A ball falls to the ground from height h and bounces to height h'. Momentum is conserved in the ball-earth system

Accepted Answer

A)   no matter what height h' it reaches.
B)   only if h' 
C)   only if h' = h.
D)   only if h' > h.
E)   only if h' ≥ h.F) A) and E)
G) A) and D)

Question 3

A 5.0-kg mass with an initial velocity of 4.0 m/s, east collides with a 4.0-kg mass with an initial velocity of 3.0 m/s, west. After the collision the 5.0-kg mass has a velocity of 1.2 m/s, south. What is the magnitude of the velocity of the 4.0-kg mass after the collision?

Accepted Answer

A)   2.0 m/s
B)   1.5 m/s
C)   1.0 m/s
D)   2.5 m/s
E)   3.0 m/sF) None of the above
G) A) and B)

Question 4

Two blocks with masses 2.0 kg and 3.0 kg are placed on a horizontal frictionless surface. A light spring is placed in a horizontal position between the blocks. The blocks are pushed together, compressing the spring, and then released from rest. After contact with the spring ends, the 3.0-kg mass has a speed of 2.0 m/s. How much potential energy was stored in the spring when the blocks were released?

Accepted Answer

A)   15 J
B)   3.0 J
C)   6.0 J
D)   12 J
E)   9.0 JF) C) and D)
G) A) and E)

Question 5

High-speed stroboscopic photographs show that the head of a golf club of mass 200 grams is traveling at 55.0 m/s just before it strikes a 46.0-gram golf ball at rest on a tee. After the collision, the clubhead travels (in the same direction) at 40.0 m/s. Find the speed of the golf ball just after impact.

Accepted Answer

The answer of High-speed stroboscopic photographs show that the head...

Question 6

A 1.6-kg ball is attached to the end of a 0.40-m string to form a pendulum. This pendulum is released from rest with the string horizontal. At the lowest point of its swing, when it is moving horizontally, the ball collides with a 0.80-kg block initially at rest on a horizontal frictionless surface. The speed of the block just after the collision is 3.0 m/s. What is the speed of the ball just after the collision?

Accepted Answer

A)   1.7 m/s
B)   1.1 m/s
C)   1.5 m/s
D)   1.3 m/s
E)   2.1 m/sF) A) and B)
G) C) and E)

Question 7

A 1.2-kg object moving with a speed of 8.0 m/s collides perpendicularly with a wall and emerges with a speed of 6.0 m/s in the opposite direction. If the object is in contact with the wall for 2.0 ms, what is the magnitude of the average force on the object by the wall?

Accepted Answer

A)   9.8 kN
B)   8.4 kN
C)   7.7 kN
D)   9.1 kN
E)   1.2 kNF) B) and E)
G) C) and D)

Question 8

A 500-g firework explodes into two pieces of equal mass at an instant when it is traveling straight up at 10 m/s. If one half shoots off horizontally to the left at 20 m/s, what is the velocity, in m/s, of the other half immediately after the explosion? (The x axis is directed right; the y axis up.)

Accepted Answer

A)  
B)  
C)  
D)  
E)  F) None of the above
G) A) and B)

Question 9

A 2.4-kg ball falling vertically hits the floor with a speed of 2.5 m/s and rebounds with a speed of 1.5 m/s. What is the magnitude of the impulse exerted on the ball by the floor?

Accepted Answer

A)   9.6 N s
B)   2.4 N s
C)   6.4 N s
D)   1.6 N s
E)   1.0 N sF) A) and E)
G) A) and D)

Question 10

In an elastic collision between two bodies of equal mass, with body 2 initially at rest, body 1 moves off at angle θ relative to the direction of its initial velocity and body 2 at angle φ. The sine of the sum of θ and φ, sin(θ + φ) , is equal to

Accepted Answer

A)   0.
B)   0.500.
C)   0.707.
D)   0.866.
E)   1.00.F) C) and D)
G) A) and E)

Question 11

A 5.0-g particle moving 60 m/s collides with a 2.0-g particle initially at rest. After the collision each of the particles has a velocity that is directed 30° from the original direction of motion of the 5.0-g particle. What is the speed of the 2.0-g particle after the collision?

Accepted Answer

A)   72 m/s
B)   87 m/s
C)   79 m/s
D)   94 m/s
E)   67 m/sF) C) and D)
G) A) and B)

Question 12

Stan argues that momentum cannot be conserved when a collision is not a head-on collision. Rachel insists it is conserved because each body receives an impulse of equal magnitude. Rachel is correct because

Accepted Answer

A)   each body exerts an equal and opposite force on the other during the collision.
B)   the forces act during equal time intervals.
C)   the law of conservation of momentum for an isolated system is a vector equation.
D)   of all of the above.
E)   of only (a)  and (b)  above.F) B) and D)
G) All of the above

Question 13

A 3.0-kg mass sliding on a frictionless surface explodes into three 1.0-kg masses. After the explosion the velocities of the three masses are: (1)  9.0 m/s, north; (2)  4.0 m/s, 30° south of west; and (3)  4.0 m/s, 30° south of east. What was the magnitude of the original velocity of the 3.0-kg mass?

Accepted Answer

A)   1.7 m/s
B)   1.0 m/s
C)   1.3 m/s
D)   2.0 m/s
E)   2.8 m/sF) C) and D)
G) None of the above

Question 14

A rocket with an initial mass of 1000 kg adjusts its thrust by varying the rate at which mass is ejected. The ejection speed relative to the rocket is 40 km/s. If the acceleration of the rocket is to have a magnitude of 20 m/s2 at an instant when its mass is 80% of the original mass, at what rate is mass being ejected at that instant? Ignore any external forces on the rocket.

Accepted Answer

A)   0.40 kg/s
B)   0.50 kg/s
C)   0.60 kg/s
D)   0.70 kg/s
E)   0.80 kg/sF) A) and B)
G) B) and D)

Question 15

An astronaut outside a spaceship hammers a loose rivet back in place. What happens to the astronaut as he swings the hammer?

Accepted Answer

A)   Nothing. The spaceship takes up the momentum of the hammer.
B)   He moves away from the spaceship.
C)   He moves towards the spaceship.
D)   He moves towards the spaceship as he pulls the hammer back and moves away from it as he swings the hammer forward.
E)   He moves away from the spaceship as he pulls the hammer back and moves toward it as he swings the hammer forward.F) B) and D)
G) A) and E)

Question 16

A 4.0-kg particle is moving horizontally with a speed of 5.0 m/s when it strikes a vertical wall. The particle rebounds with a speed of 3.0 m/s. What is the magnitude of the impulse delivered to the particle?

Accepted Answer

A)   24 N⋅s
B)   32 N⋅s
C)   40 N⋅s
D)   30 N⋅s
E)   8.0 N⋅sF) A) and E)
G) A) and D)

Question 17

A 1.0-kg object moving 9.0 m/s collides with a 2.0-kg object moving 6.0 m/s in a direction that is perpendicular to the initial direction of motion of the 1.0-kg object. The two masses remain together after the collision, and this composite object then collides with and sticks to a 3.0-kg object. After these collisions, the final composite (6.0-kg)  object remains at rest. What was the speed of the 3.0-kg object before the collisions?

Accepted Answer

A)   15 m/s
B)   10 m/s
C)   5.0 m/s
D)   20 m/s
E)   25 m/sF) A) and B)
G) B) and E)

Question 18

A 4.0-kg mass has a velocity of 4.0 m/s, east when it explodes into two 2.0-kg masses. After the explosion one of the masses has a velocity of 3.0 m/s at an angle of 60° north of east. What is the magnitude of the velocity of the other mass after the explosion?

Accepted Answer

A)   7.9 m/s
B)   8.9 m/s
C)   7.0 m/s
D)   6.1 m/s
E)   6.7 m/sF) B) and E)
G) A) and D)

Question 19

The speed of a 2.0-kg object changes from 30 m/s to 40 m/s during a 5.0-s time interval. During this same time interval, the velocity of the object changes its direction by 90°. What is the magnitude of the average total force acting on the object during this time interval?

Accepted Answer

A)   30 N
B)   20 N
C)   40 N
D)   50 N
E)   6.0 NF) A) and B)
G) None of the above

Question 20

A ball of mass mB is released from rest and acquires velocity of magnitude vB before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is

Accepted Answer

A)   0.
B)  B is released from rest and acquires velocity of magnitude vB before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is 
A)   0. 
B)     . 
C)     . 
D)   1 
E)     ." class="answers-bank-image d-inline" rel="preload" > .
C)  B is released from rest and acquires velocity of magnitude vB before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is 
A)   0. 
B)     . 
C)     . 
D)   1 
E)     ." class="answers-bank-image d-inline" rel="preload" > .
D)   1
E)  B is released from rest and acquires velocity of magnitude vB before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is 
A)   0. 
B)     . 
C)     . 
D)   1 
E)     ." class="answers-bank-image d-inline" rel="preload" > .F) A) and B)
G) A) and C)

Exam 9: Linear Momentum and Collisions

A 5.0-kg mass with an initial velocity of 4.0 m/s, east collides with a 4.0-kg mass with an initial velocity of 3.0 m/s, west. After the collision the 5.0-kg mass has a velocity of 1.2 m/s, south. What is the magnitude of the velocity of the 4.0-kg mass after the collision?

Correct Answer
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Correct Answer
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A 4.0-kg mass has a velocity of 4.0 m/s, east when it explodes into two 2.0-kg masses. After the explosion one of the masses has a velocity of 3.0 m/s at an angle of 60° north of east. What is the magnitude of the velocity of the other mass after the explosion?

Correct Answer
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Correct Answer
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A 500-g firework explodes into two pieces of equal mass at an instant when it is traveling straight up at 10 m/s. If one half shoots off horizontally to the left at 20 m/s, what is the velocity, in m/s, of the other half immediately after the explosion? (The x axis is directed right; the y axis up.)

Correct Answer
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A ball falls to the ground from height h and bounces to height h'. Momentum is conserved in the ball-earth system

Correct Answer
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Correct Answer
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A 3.0-kg mass sliding on a frictionless surface explodes into three 1.0-kg masses. After the explosion the velocities of the three masses are: (1) 9.0 m/s, north; (2) 4.0 m/s, 30° south of west; and (3) 4.0 m/s, 30° south of east. What was the magnitude of the original velocity of the 3.0-kg mass?

Correct Answer
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In an elastic collision between two bodies of equal mass, with body 2 initially at rest, body 1 moves off at angle θ relative to the direction of its initial velocity and body 2 at angle φ. The sine of the sum of θ and φ, sin(θ + φ) , is equal to

Correct Answer
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Correct Answer
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Correct Answer
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Stan argues that momentum cannot be conserved when a collision is not a head-on collision. Rachel insists it is conserved because each body receives an impulse of equal magnitude. Rachel is correct because

Correct Answer
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An exam paper contains the following equation for rocket propulsion: . The error in the equation is that, instead of (v + v_e) , the velocity of the fuel relative to the ground should be

Correct Answer
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A ball of mass m_B is released from rest and acquires velocity of magnitude v_B before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is

Correct Answer
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A 4.0-kg particle is moving horizontally with a speed of 5.0 m/s when it strikes a vertical wall. The particle rebounds with a speed of 3.0 m/s. What is the magnitude of the impulse delivered to the particle?

Correct Answer
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A 2.4-kg ball falling vertically hits the floor with a speed of 2.5 m/s and rebounds with a speed of 1.5 m/s. What is the magnitude of the impulse exerted on the ball by the floor?

Correct Answer
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A 1.2-kg object moving with a speed of 8.0 m/s collides perpendicularly with a wall and emerges with a speed of 6.0 m/s in the opposite direction. If the object is in contact with the wall for 2.0 ms, what is the magnitude of the average force on the object by the wall?

Correct Answer
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A 5.0-g particle moving 60 m/s collides with a 2.0-g particle initially at rest. After the collision each of the particles has a velocity that is directed 30° from the original direction of motion of the 5.0-g particle. What is the speed of the 2.0-g particle after the collision?

Correct Answer
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An astronaut outside a spaceship hammers a loose rivet back in place. What happens to the astronaut as he swings the hammer?

Correct Answer
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The speed of a 2.0-kg object changes from 30 m/s to 40 m/s during a 5.0-s time interval. During this same time interval, the velocity of the object changes its direction by 90°. What is the magnitude of the average total force acting on the object during this time interval?

Correct Answer
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Exam 9: Linear Momentum and Collisions

A 5.0-kg mass with an initial velocity of 4.0 m/s, east collides with a 4.0-kg mass with an initial velocity of 3.0 m/s, west. After the collision the 5.0-kg mass has a velocity of 1.2 m/s, south. What is the magnitude of the velocity of the 4.0-kg mass after the collision?

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Correct AnswerverifiedShow Answer

A 4.0-kg mass has a velocity of 4.0 m/s, east when it explodes into two 2.0-kg masses. After the explosion one of the masses has a velocity of 3.0 m/s at an angle of 60° north of east. What is the magnitude of the velocity of the other mass after the explosion?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

A ball falls to the ground from height h and bounces to height h'. Momentum is conserved in the ball-earth system

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

In an elastic collision between two bodies of equal mass, with body 2 initially at rest, body 1 moves off at angle θ relative to the direction of its initial velocity and body 2 at angle φ. The sine of the sum of θ and φ, sin(θ + φ) , is equal to

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Stan argues that momentum cannot be conserved when a collision is not a head-on collision. Rachel insists it is conserved because each body receives an impulse of equal magnitude. Rachel is correct because

Correct AnswerverifiedShow Answer

An exam paper contains the following equation for rocket propulsion: . The error in the equation is that, instead of (v + ve) , the velocity of the fuel relative to the ground should be

Correct AnswerverifiedShow Answer

A ball of mass mB is released from rest and acquires velocity of magnitude vB before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is

Correct AnswerverifiedShow Answer

A 4.0-kg particle is moving horizontally with a speed of 5.0 m/s when it strikes a vertical wall. The particle rebounds with a speed of 3.0 m/s. What is the magnitude of the impulse delivered to the particle?

Correct AnswerverifiedShow Answer

A 2.4-kg ball falling vertically hits the floor with a speed of 2.5 m/s and rebounds with a speed of 1.5 m/s. What is the magnitude of the impulse exerted on the ball by the floor?

Correct AnswerverifiedShow Answer

A 1.2-kg object moving with a speed of 8.0 m/s collides perpendicularly with a wall and emerges with a speed of 6.0 m/s in the opposite direction. If the object is in contact with the wall for 2.0 ms, what is the magnitude of the average force on the object by the wall?

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A 5.0-g particle moving 60 m/s collides with a 2.0-g particle initially at rest. After the collision each of the particles has a velocity that is directed 30° from the original direction of motion of the 5.0-g particle. What is the speed of the 2.0-g particle after the collision?

Correct AnswerverifiedShow Answer

An astronaut outside a spaceship hammers a loose rivet back in place. What happens to the astronaut as he swings the hammer?

Correct AnswerverifiedShow Answer

The speed of a 2.0-kg object changes from 30 m/s to 40 m/s during a 5.0-s time interval. During this same time interval, the velocity of the object changes its direction by 90°. What is the magnitude of the average total force acting on the object during this time interval?

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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An exam paper contains the following equation for rocket propulsion: . The error in the equation is that, instead of (v + v_e) , the velocity of the fuel relative to the ground should be

Correct Answer
verified

A ball of mass m_B is released from rest and acquires velocity of magnitude v_B before hitting the ground. The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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