Question 1

Which of the following have the highest ratio of momentum to kinetic energy,p/K?

Accepted Answer

A) an asteroid with mass 106 kg and speed 500 m/s 
B) a high-speed train with a mass of 180,000 kg and a speed of 300 km/hr 
C) a 120-kg linebacker with a speed of 10 m/s 
D) a 10-kg cannon with a speed of 120 m/s 
E) a proton with a mass of 6 * 10-27 kg and a speed of 2 *105 m/s 
A) an asteroid with mass 106 kg and speed 500 m/s 
B) a high-speed train with a mass of 180,000 kg and a speed of 300 km/hr 
C) a 120-kg linebacker with a speed of 10 m/s 
D) a 10-kg cannon with a speed of 120 m/s 
E) a proton with a mass of 6 * 10-27 kg and a speed of 2 *105 m/s

Question 2

A pendulum with a mass M swings and picks up a piece of clay of mass m at the bottom of its swing.

Accepted Answer

A) It rises to the same height after the collision as before. 
B) The total mechanical energy of the system is unchanged by the collision. 
C) If M = m,then the height it reaches after the collision is half that before the collision. 
D) If M = m,then the height it reaches after the collision is 1/4 that before the collision. 
E) If M = m,then it rises to twice the height it had before the collision. 
A) It rises to the same height after the collision as before. 
B) The total mechanical energy of the system is unchanged by the collision. 
C) If M = m,then the height it reaches after the collision is half that before the collision. 
D) If M = m,then the height it reaches after the collision is 1/4 that before the collision. 
E) If M = m,then it rises to twice the height it had before the collision.

Question 3

Throwing caution to the wind,Bob hops off a bridge onto a small boat that is travelling under the bridge at 12.0 m/s.If Bob's mass is 85.0 kg,and the boat's (with its driver)is 451 kg,how fast is the boat moving after Bob lands on it? Assume Bob falls straight down into the boat.

Accepted Answer

A) 9.7 m/s 
B) 10.1 m/s 
C) 11.0 m/s 
D) 14.3 m/s 
A) 9.7 m/s 
B) 10.1 m/s 
C) 11.0 m/s 
D) 14.3 m/s

Question 4

A golf ball bounces to a height of 7.60 m after its second bounce after being dropped onto the sidewalk from a 20.5-m high pedestrian overpass.What is the coefficient of restitution for the golf ball -- sidewalk collision?

Accepted Answer

A) 0.609 
B) 0.551 
C) 0.780 
D) 0.371 
E) 1 
A) 0.609 
B) 0.551 
C) 0.780 
D) 0.371 
E) 1

Question 5

An object (m = 0.05 kg)with velocity 20 m/s collides head on with another with mass 0.10 kg at rest.If the first object has a velocity = 0 after the collision,what is the loss in kinetic energy (J)in the collision?

Accepted Answer

A) 10 
B) 2 
C) 3 
D) 4 
E) 5 
A) 10 
B) 2 
C) 3 
D) 4 
E) 5

Question 6

An explosion inside a mortar tube launches a 100-kg projectile directly upward with a speed of 350 m/s.The increase in the Earth's kinetic energy due to this explosion is (mass of the Earth is

Accepted Answer

A) 3.50 * 104 J. 
B) 1.02 * 10-16 J. 
C) 1.22 * 107 J. 
D) 6.35 * 10-7 J. 
E) 8.92 * 102 J. 
A) 3.50 * 104 J. 
B) 1.02 * 10-16 J. 
C) 1.22 * 107 J. 
D) 6.35 * 10-7 J. 
E) 8.92 * 102 J.

Question 7

Particle one of mass m initially moves to the right at v.Particle two of mass 3m is initially at rest.After they undergo an elastic collision,particle one moves directly down.In what direction does particle two move relative to the initial direction of particle one?

Accepted Answer

A) 63o 
B) 60o 
C) 35o 
D) 30o 
E) 26o 
A) 63o 
B) 60o 
C) 35o 
D) 30o 
E) 26o

Question 8

A 8-kg object with a velocity 5   m/s explodes into two fragments of equal mass.One flies off with a velocity of (3   -2   )m/s.The velocity of the other fragments is

Accepted Answer

A) 7   + 2
  m/s. 
B) 8   + 3
  m/s. 
C) 47   - 2
  m/s. 
D) 7   - 2
  
A) 7   + 2
  m/s. 
B) 8   + 3
  m/s. 
C) 47   - 2
  m/s. 
D) 7   - 2

Question 9

A 1000-kg car is travelling west at 17.0 m/s toward an intersection.A 1500-kg truck is travelling north at 20.0 m/s toward the same intersection.The car and truck collide at the intersection and stick together.What is the final kinetic energy of the system?

Accepted Answer

A) 1.36 * 105 J 
B) 1.72 * 105 J 
C) 2.38 * 105 J 
D) 4.76 * 105 J 
A) 1.36 * 105 J 
B) 1.72 * 105 J 
C) 2.38 * 105 J 
D) 4.76 * 105 J

Question 10

A spring is compressed between two blocks,block A of mass m,and block B of mass 3m.The 1250 N/m spring is released,sending the blocks in opposite directions.What is the ratio of the magnitudes of the momenta of block A to block B,pA/pB?

Accepted Answer

A) 1 
B) 1/3 
C) More information is needed. 
D) 3 
E) 1/9 
A) 1 
B) 1/3 
C) More information is needed. 
D) 3 
E) 1/9

Question 11

Two bumper cars on a frictionless surface collide elastically.The first bumper car is moving to the right with a speed of 22.0 m/s and rear-ends a bumper car also moving to the right with a speed of 5.00 m/s.What is the speed of the first bumper car after the collision (in m/s)? The mass of the first bumper car is 192 kg and the mass of the second bumper car is 144 kg.Assume that the collision takes place in one dimension.

Accepted Answer

A) 3.9643 
B) 4.6382 
C) 5.4267 
D) 6.3492 
E) 7.4286 
A) 3.9643 
B) 4.6382 
C) 5.4267 
D) 6.3492 
E) 7.4286

Question 12

In a collision between two objects,what is always conserved?

Accepted Answer

A) the momentum of each object individually 
B) the total momentum of the two objects 
C) the kinetic energy of each object individually 
D) the total kinetic energy of the two objects 
E) More than one of the choices are true. 
A) the momentum of each object individually 
B) the total momentum of the two objects 
C) the kinetic energy of each object individually 
D) the total kinetic energy of the two objects 
E) More than one of the choices are true.

Question 13

A 35-kg boy runs at 2.5 m/s and leaps onto a tire swing,the mass of which is 28 kg.If the maximum angle the swing reaches is 6.7 degrees,how long is the tire swing?

Accepted Answer

A) 5.8 m 
B) 7.2 m 
C) 14 m 
D) 26 m 
A) 5.8 m 
B) 7.2 m 
C) 14 m 
D) 26 m

Question 14

A spring is compressed between two blocks,block A of mass m,and block B of mass 3m.The 1250 N/m spring is released,sending the blocks in opposite directions.What is the ratio of kinetic energies of block A to block B,KA/KB?

Accepted Answer

A) 1/3 
B) 3 
C) 1 
D) 1/9 
E) More information is needed. 
A) 1/3 
B) 3 
C) 1 
D) 1/9 
E) More information is needed.

Question 15

A golf-ball (m = 0.045 kg)is at rest on a tee when an average force of 5880 N,directed 12 degrees above the horizon,is applied by a golf-club over a time of 0.45 ms.Find the range of the golf ball.

Accepted Answer

A) 58m 
B) 60.m 
C) 120m 
D) 140m 
A) 58m 
B) 60.m 
C) 120m 
D) 140m

Question 16

A rubber ball is dropped from a height of 8.7 m onto the floor below.It rebounds to a height of 7.2 m.What is the coefficient of restitution for the ball?

Accepted Answer

A) 0.17 
B) 0.42 
C) 0.68 
D) 0.83 
E) 0.91 
A) 0.17 
B) 0.42 
C) 0.68 
D) 0.83 
E) 0.91

Question 17

An empty railroad car traveling at a constant speed strikes a second car at rest.The second car,being full with passengers,has twice the mass of the first car.If the cars lock together as a result of the collision,the ratio of the initial to the final kinetic energies of the system is

Accepted Answer

A) 1. 
B) 1/3. 
C) 3. 
D) 1/9. 
E) 9. 
A) 1. 
B) 1/3. 
C) 3. 
D) 1/9. 
E) 9.

Question 18

A railroad water tanker car with a total mass of 1.50·105 kg rolls without friction or air resistance along a straight,level track at a constant speed of 5.74 m/s.As the car rolls it springs a leak at the bottom of the tank,releasing a stream of water going straight down.What is the speed of the car after the 6.35·104 kg of water have leaked out of the car?

Accepted Answer

A) 4.75 m/s 
B) 13.6 m/s 
C) 9.95 m/s 
D) 12.5 m/s 
E) 5.74 m/s 
A) 4.75 m/s 
B) 13.6 m/s 
C) 9.95 m/s 
D) 12.5 m/s 
E) 5.74 m/s

Question 19

A 1000-kg car is travelling west at 17.0 m/s toward an intersection.A 1500-kg truck is travelling north at 20.0 m/s toward the same intersection.The car and truck collide at the intersection and sick together.What is the angle of their velocity after the collision relative to the east direction?

Accepted Answer

A) 60.5 degrees 
B) 75.5 degrees 
C) 95.5 degrees 
D) 120 degrees 
E) 150 degrees 
A) 60.5 degrees 
B) 75.5 degrees 
C) 95.5 degrees 
D) 120 degrees 
E) 150 degrees

Question 20

Consider two carts,of masses m and 2m,at rest on a frictionless air track.If you push the first cart for 3 m and then the other for the same length of distance with the same force,which cart undergoes the smallest change in kinetic energy?

Accepted Answer

A) the cart with mass m 
B) the cart with mass 2m 
C) The change in kinetic energy is the same in each case. 
D) There is no change in kinetic energy in either cart. 
E) Impossible to tell. 
A) the cart with mass m 
B) the cart with mass 2m 
C) The change in kinetic energy is the same in each case. 
D) There is no change in kinetic energy in either cart. 
E) Impossible to tell.

Exam 7: Momentum and Collisions

Which of the following have the highest ratio of momentum to kinetic energy,p/K?

A pendulum with a mass M swings and picks up a piece of clay of mass m at the bottom of its swing.

Throwing caution to the wind,Bob hops off a bridge onto a small boat that is travelling under the bridge at 12.0 m/s.If Bob's mass is 85.0 kg,and the boat's (with its driver)is 451 kg,how fast is the boat moving after Bob lands on it? Assume Bob falls straight down into the boat.

A golf ball bounces to a height of 7.60 m after its second bounce after being dropped onto the sidewalk from a 20.5-m high pedestrian overpass.What is the coefficient of restitution for the golf ball -- sidewalk collision?

An object (m = 0.05 kg)with velocity 20 m/s collides head on with another with mass 0.10 kg at rest.If the first object has a velocity = 0 after the collision,what is the loss in kinetic energy (J)in the collision?

An explosion inside a mortar tube launches a 100-kg projectile directly upward with a speed of 350 m/s.The increase in the Earth's kinetic energy due to this explosion is (mass of the Earth is

Particle one of mass m initially moves to the right at v.Particle two of mass 3m is initially at rest.After they undergo an elastic collision,particle one moves directly down.In what direction does particle two move relative to the initial direction of particle one?

A 8-kg object with a velocity 5 m/s explodes into two fragments of equal mass.One flies off with a velocity of (3 -2 )m/s.The velocity of the other fragments is

A 1000-kg car is travelling west at 17.0 m/s toward an intersection.A 1500-kg truck is travelling north at 20.0 m/s toward the same intersection.The car and truck collide at the intersection and stick together.What is the final kinetic energy of the system?

A spring is compressed between two blocks,block A of mass m,and block B of mass 3m.The 1250 N/m spring is released,sending the blocks in opposite directions.What is the ratio of the magnitudes of the momenta of block A to block B,pA/pB?

In a collision between two objects,what is always conserved?

A 35-kg boy runs at 2.5 m/s and leaps onto a tire swing,the mass of which is 28 kg.If the maximum angle the swing reaches is 6.7 degrees,how long is the tire swing?

A spring is compressed between two blocks,block A of mass m,and block B of mass 3m.The 1250 N/m spring is released,sending the blocks in opposite directions.What is the ratio of kinetic energies of block A to block B,KA/KB?

A golf-ball (m = 0.045 kg)is at rest on a tee when an average force of 5880 N,directed 12 degrees above the horizon,is applied by a golf-club over a time of 0.45 ms.Find the range of the golf ball.

A rubber ball is dropped from a height of 8.7 m onto the floor below.It rebounds to a height of 7.2 m.What is the coefficient of restitution for the ball?

An empty railroad car traveling at a constant speed strikes a second car at rest.The second car,being full with passengers,has twice the mass of the first car.If the cars lock together as a result of the collision,the ratio of the initial to the final kinetic energies of the system is

A 1000-kg car is travelling west at 17.0 m/s toward an intersection.A 1500-kg truck is travelling north at 20.0 m/s toward the same intersection.The car and truck collide at the intersection and sick together.What is the angle of their velocity after the collision relative to the east direction?

Consider two carts,of masses m and 2m,at rest on a frictionless air track.If you push the first cart for 3 m and then the other for the same length of distance with the same force,which cart undergoes the smallest change in kinetic energy?

Overview

Motion in a Straight Line

Motion in Two and Three Dimensions

Force

Kinetic Energy, work, and Power

Potential Energy and Energy Conservation

Systems of Particles and Extended Objects

Circular Motion

Rotation

Static Equilibrium

Gravitation

Solids and Fluids

Oscillations

Waves

Sound

Temperature

Heat and the First Law of Thermodynamics

Ideal Gases

The Second Law of Thermodynamics

Electrostatics

Electric Fields and Gausss Law

Electric Potential

Capacitors

Current and Resistance

Direct Current Circuits

Magnetism

Magnetic Fields of Moving Charges

Electromagnetic Induction

Alternating Current Circuits

Electromagnetic Waves

Geometric Optics

Lenses and Optical Instruments

Wave Optics

Relativity

Quantum Physics

Quantum Mechanics

Atomic Physics

Elementary Particle Physics

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Filters

A spring is compressed between two blocks,block A of mass m,and block B of mass 3m.The 1250 N/m spring is released,sending the blocks in opposite directions.What is the ratio of the magnitudes of the momenta of block A to block B,p_A/p_B?

A spring is compressed between two blocks,block A of mass m,and block B of mass 3m.The 1250 N/m spring is released,sending the blocks in opposite directions.What is the ratio of kinetic energies of block A to block B,K_A/K_B?