Question 1

A force of 10 N holds an ideal spring with a 20-N/m spring constant in compression.The potential energy stored in the spring is:

Accepted Answer

A) 0.5 J 
B) 2.5 J 
C) 5 J 
D) 10 J 
E) 200 J 
A) 0.5 J 
B) 2.5 J 
C) 5 J 
D) 10 J 
E) 200 J B

Question 2

The potential energy for the interaction between the two atoms in a diatomic molecule is U = A/x12 - B/x6, where A and B are constants and x is the interatomic distance.The magnitude of the force that one atom exerts on the other is:

Accepted Answer

A) 12A/x13 - 6B/x7 
B) -13A/x13 + 7B/x7 
C) -11A/x11 + 5B/x5 
D) 72A/x12 - 72B/x6 
E) A/x13 - B/x7 
A) 12A/x13 - 6B/x7 
B) -13A/x13 + 7B/x7 
C) -11A/x11 + 5B/x5 
D) 72A/x12 - 72B/x6 
E) A/x13 - B/x7 A

Question 3

A force on a particle is conservative if:

Accepted Answer

A) its work equals the change in the kinetic energy of the particle 
B) it obeys Newton's second law 
C) it obeys Newton's third law 
D) its work depends on the end points of the motion, not this the path between 
E) it is not a frictional force 
A) its work equals the change in the kinetic energy of the particle 
B) it obeys Newton's second law 
C) it obeys Newton's third law 
D) its work depends on the end points of the motion, not this the path between 
E) it is not a frictional force D

Question 4

The potential energy of a 0.20-kg particle moving along the x axis is given by U(x)=(8.0 J/m2)x2 + (2.0 J/m4)x4.
When the particle is at x = 1.0 m it is traveling in the positive x direction with a speed of 5.0 m/s.It next stops momentarily to turn around at x =

Accepted Answer

A) 0 m 
B) -1.1 m 
C) 1.1 m 
D) -2.3 m 
E) 2.3 m 
A) 0 m 
B) -1.1 m 
C) 1.1 m 
D) -2.3 m 
E) 2.3 m

Question 5

A 0.75-kg block slides on a rough horizontal table top.Just before it hits a horizontal ideal spring its speed is 3.5 m/s.It compresses the spring 5.7 cm before coming to rest.If the spring constant is 1200 N/m, the thermal energy of the block and the table top must have:

Accepted Answer

A) not changed 
B) decreased by 1.9 J 
C) decreased by 2.6 J 
D) increased by 1.9 J 
E) increased by 2.6 J 
A) not changed 
B) decreased by 1.9 J 
C) decreased by 2.6 J 
D) increased by 1.9 J 
E) increased by 2.6 J

Question 6

Which of the five graphs correctly shows the potential energy of a spring as a function of its elongation x?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 7

The wound spring of a clock possesses:

Accepted Answer

A) kinetic but no potential energy 
B) potential but no kinetic energy 
C) both potential and kinetic energy in equal amounts 
D) neither potential nor kinetic energy 
E) both potential and kinetic energy, but more kinetic energy than potential energy 
A) kinetic but no potential energy 
B) potential but no kinetic energy 
C) both potential and kinetic energy in equal amounts 
D) neither potential nor kinetic energy 
E) both potential and kinetic energy, but more kinetic energy than potential energy

Question 8

A small object of mass m starts at rest at the position shown and slides along the frictionless loop-the-loop track of radius R.What is the smallest value of y such that the object will slide without losing contact with the track?

Accepted Answer

A) R/4 
B) R/2 
C) R 
D) 2R 
E) 0 
A) R/4 
B) R/2 
C) R 
D) 2R 
E) 0

Question 9

Two objects interact with each other and with no other objects.Initially object A has a speed of 5 m/s and object B has a speed of 10 m/s.In the course of their motion they return to their initial positions.Then A has a speed of 4 m/s and B has a speed of 7 m/s.We can conclude:

Accepted Answer

A) the potential energy changed from the beginning to the end of the trip 
B) mechanical energy was increased by nonconservative forces 
C) mechanical energy was decreased by nonconservative forces 
D) mechanical energy was increased by conservative forces 
E) mechanical energy was decreased by conservative forces 
A) the potential energy changed from the beginning to the end of the trip 
B) mechanical energy was increased by nonconservative forces 
C) mechanical energy was decreased by nonconservative forces 
D) mechanical energy was increased by conservative forces 
E) mechanical energy was decreased by conservative forces

Question 10

Suppose that the fundamental dimensions are taken to be: force (F), velocity (V)and time (T).The dimensions of potential energy are then:

Accepted Answer

A) F/T 
B) FVT 
C) FV/T 
D) F/T2 
E) FV2/T2 
A) F/T 
B) FVT 
C) FV/T 
D) F/T2 
E) FV2/T2

Question 11

A rectangular block is moving along a frictionless path when it encounters the circular loop as shown.The block passes points 1,2,3,4,1 before returning to the horizontal track.At point 3:

Accepted Answer

A) its mechanical energy is a minimum 
B) the forces on it are balanced 
C) it is not accelerating 
D) its speed is a minimum 
E) it experiences a net upward force 
A) its mechanical energy is a minimum 
B) the forces on it are balanced 
C) it is not accelerating 
D) its speed is a minimum 
E) it experiences a net upward force

Question 12

A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface.When the spring is 4.0 cm longer than its equilibrium length, the speed of the block is 0.50 m/s.The greatest speed of the block is:

Accepted Answer

A) 0.32 m/s 
B) 0.55 m/s 
C) 0.71 m/s 
D) 0.87 m/s 
E) 0.93 m/s 
A) 0.32 m/s 
B) 0.55 m/s 
C) 0.71 m/s 
D) 0.87 m/s 
E) 0.93 m/s

Question 13

The potential energy of a particle moving along the x axis is given by U(x)= (8.0 J/m2)x2 + (2.0 J/m4)x4.
If the total mechanical energy is 9.0 J, the limits of motion are:

Accepted Answer

A) -0.96 m; +0.96 m 
B) -2.2 m; +2.2 m 
C) -1.6 m; +1.6 m 
D) -0.96 m; +2.2 m 
E) -0.96 m; +1.6 m 
A) -0.96 m; +0.96 m 
B) -2.2 m; +2.2 m 
C) -1.6 m; +1.6 m 
D) -0.96 m; +2.2 m 
E) -0.96 m; +1.6 m

Question 14

Three identical blocks move either on a horizontal surface, up a plane, or down a plane, as shown below.They all start with the same speed and continue to move until brought to rest by friction.Rank the three situations according to the mechanical energy dissipated by friction, least to greatest.

Accepted Answer

A) The same for all cases 
B) 1, 2, 3 
C) 1, then 2 and 3 tie 
D) 3, 1, 2 
E) 2, 1, 3 
A) The same for all cases 
B) 1, 2, 3 
C) 1, then 2 and 3 tie 
D) 3, 1, 2 
E) 2, 1, 3

Question 15

A 2.2-kg block starts from rest on a rough inclined plane that makes an angle of 25° with the horizontal.The coefficient of kinetic friction is 0.25.As the block goes 2.0 m down the plane, the mechanical energy of the Earth-block system changes by:

Accepted Answer

A) 0 J 
B) -9.8 J 
C) 9.8 J 
D) -18 J 
E) 18 J 
A) 0 J 
B) -9.8 J 
C) 9.8 J 
D) -18 J 
E) 18 J

Question 16

An ideal spring is used to fire a 15.0-g block horizontally.The spring has a spring constant of 20 N/m and is initially compressed by 7.0 cm.The kinetic energy of the block as it leaves the spring is:

Accepted Answer

A) 0 J 
B) 2.5 * 10-2 J 
C) 4.9 *10-2 J 
D) 9.8 * 10-2 J 
E) 1.4 J 
A) 0 J 
B) 2.5 * 10-2 J 
C) 4.9 *10-2 J 
D) 9.8 * 10-2 J 
E) 1.4 J

Question 17

A ball of mass m, at one end of a string of length L, rotates in a vertical circle just fast enough to prevent the string from going slack at the top of the circle.Assuming mechanical energy is conserved, the speed of the ball at the bottom of the circle is:

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 18

A 25-g ball is released from rest 80 m above the surface of the Earth.During the fall the total thermal energy of the ball and air increases by15 J.Just before it hits the surface its speed is

Accepted Answer

A) 19 m/s 
B) 35 m/s 
C) 40 m/s 
D) 45 m/s 
E) 53 m/s 
A) 19 m/s 
B) 35 m/s 
C) 40 m/s 
D) 45 m/s 
E) 53 m/s

Question 19

A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface.The total mechanical energy is 0.12 J.The greatest speed of the block is:

Accepted Answer

A) 0.15 m/s 
B) 0.24 m/s 
C) 0.49 m/s 
D) 0.69 m/s 
E) 1.46 m/s 
A) 0.15 m/s 
B) 0.24 m/s 
C) 0.49 m/s 
D) 0.69 m/s 
E) 1.46 m/s

Question 20

A block is released from rest at point P and slides along the frictionless track shown.At point Q, its speed is:

Accepted Answer

A)    
B) 2g(h1 - h2) 
C) (h1 - h2)/2g 
D)    
E) (h1 - h2)2/2g 
A)    
B) 2g(h1 - h2) 
C) (h1 - h2)/2g 
D)    
E) (h1 - h2)2/2g

Exam 8: Potential Energy and Conservation of Energy

A force of 10 N holds an ideal spring with a 20-N/m spring constant in compression.The potential energy stored in the spring is:

The potential energy for the interaction between the two atoms in a diatomic molecule is U = A/x12 - B/x6, where A and B are constants and x is the interatomic distance.The magnitude of the force that one atom exerts on the other is:

A force on a particle is conservative if:

The potential energy of a 0.20-kg particle moving along the x axis is given by U(x)=(8.0 J/m2)x2 + (2.0 J/m4)x4. When the particle is at x = 1.0 m it is traveling in the positive x direction with a speed of 5.0 m/s.It next stops momentarily to turn around at x =

A 0.75-kg block slides on a rough horizontal table top.Just before it hits a horizontal ideal spring its speed is 3.5 m/s.It compresses the spring 5.7 cm before coming to rest.If the spring constant is 1200 N/m, the thermal energy of the block and the table top must have:

Which of the five graphs correctly shows the potential energy of a spring as a function of its elongation x?

The wound spring of a clock possesses:

A small object of mass m starts at rest at the position shown and slides along the frictionless loop-the-loop track of radius R.What is the smallest value of y such that the object will slide without losing contact with the track?

Two objects interact with each other and with no other objects.Initially object A has a speed of 5 m/s and object B has a speed of 10 m/s.In the course of their motion they return to their initial positions.Then A has a speed of 4 m/s and B has a speed of 7 m/s.We can conclude:

Suppose that the fundamental dimensions are taken to be: force (F), velocity (V)and time (T).The dimensions of potential energy are then:

A rectangular block is moving along a frictionless path when it encounters the circular loop as shown.The block passes points 1,2,3,4,1 before returning to the horizontal track.At point 3:

A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface.When the spring is 4.0 cm longer than its equilibrium length, the speed of the block is 0.50 m/s.The greatest speed of the block is:

The potential energy of a particle moving along the x axis is given by U(x)= (8.0 J/m2)x2 + (2.0 J/m4)x4. If the total mechanical energy is 9.0 J, the limits of motion are:

Three identical blocks move either on a horizontal surface, up a plane, or down a plane, as shown below.They all start with the same speed and continue to move until brought to rest by friction.Rank the three situations according to the mechanical energy dissipated by friction, least to greatest.

A 2.2-kg block starts from rest on a rough inclined plane that makes an angle of 25° with the horizontal.The coefficient of kinetic friction is 0.25.As the block goes 2.0 m down the plane, the mechanical energy of the Earth-block system changes by:

An ideal spring is used to fire a 15.0-g block horizontally.The spring has a spring constant of 20 N/m and is initially compressed by 7.0 cm.The kinetic energy of the block as it leaves the spring is:

A ball of mass m, at one end of a string of length L, rotates in a vertical circle just fast enough to prevent the string from going slack at the top of the circle.Assuming mechanical energy is conserved, the speed of the ball at the bottom of the circle is:

A 25-g ball is released from rest 80 m above the surface of the Earth.During the fall the total thermal energy of the ball and air increases by15 J.Just before it hits the surface its speed is

A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface.The total mechanical energy is 0.12 J.The greatest speed of the block is:

A block is released from rest at point P and slides along the frictionless track shown.At point Q, its speed is:

Measurement

Motion Along a Straight Line

Vectors

Motion in Two and Three Dimensions

Force and Motion

Force and Motion

Kinetic Energy and Work

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves

Waves

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Coulombs Law

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference 1

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

The potential energy for the interaction between the two atoms in a diatomic molecule is U = A/x¹² - B/x⁶, where A and B are constants and x is the interatomic distance.The magnitude of the force that one atom exerts on the other is:

The potential energy of a 0.20-kg particle moving along the x axis is given by U(x)=(8.0 J/m²)x²+ (2.0 J/m⁴)x^4. When the particle is at x = 1.0 m it is traveling in the positive x direction with a speed of 5.0 m/s.It next stops momentarily to turn around at x =

The potential energy of a particle moving along the x axis is given by U(x)= (8.0 J/m²)x² + (2.0 J/m⁴)x⁴. If the total mechanical energy is 9.0 J, the limits of motion are: