Question 1

A projectile of mass 0.50 kg is fired with an initial speed of 10 m/s at an angle of 60 ° above the horizontal. The potential energy of the projectile-Earth system when the projectile is at its highest point (relative to the potential energy when the projectile is at ground level)  is:

Accepted Answer

A)   25 J
B)   18.75 J
C)   12.5 J
D)   6.25 J
E)   none of theseF) A) and B)
G) A) and E)

Question 2

The diagram shows a plot of the potential energy as a function of x for a particle moving along the x axis. The points of unstable equilibrium are:

Accepted Answer

A)   only a
B)   only b
C)   only c
D)   only d
E)   b and dF) A) and E)
G) A) and B)

Question 3

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 of one atom exerts on the other is: 12 - B/x6, where A and B are constants and x is the interatomic distance. The magnitude of the force of one atom exerts on the other is:   A)  12A/|x|13 - 6B/|x|7 B)  -13A/|x|13 + 7B/|x|7 C)  -11A/|x|11 + 5B/|x|5 D)  72A/|x|12 - 72B/|x|6 E)  A/|x|13 - B/|x|7" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   12A/|x|13 - 6B/|x|7
B)   -13A/|x|13 + 7B/|x|7
C)   -11A/|x|11 + 5B/|x|5
D)   72A/|x|12 - 72B/|x|6
E)   A/|x|13 - B/|x|7F) A) and B)
G) All of the above

Question 4

A golf ball is struck by a golf club and falls on a green eight feet above the tee. The potential energy of the Earth-ball system is greatest:

Accepted Answer

A)   just before the ball is struck
B)   just after the ball is struck
C)   just after the ball lands on the green
D)   when the ball comes to rest on the green
E)   when the ball reaches the highest point in its flightF) A) and B)
G) A) and C)

Question 5

The sum of the kinetic and potential energies of a system of objects is conserved:

Accepted Answer

A)   only when no external force acts on the objects
B)   only when the objects move along closed paths
C)   only when the work done by the resultant external force is zero
D)   always
E)   none of the aboveF) All of the above
G) A) and D)

Question 6

A 700-N man jumps out of a window into a fire net 10 m below. The net stretches 2 m before bringing the man to rest and tossing him back into the air. The maximum potential energy of the net, compared to it's unstretched potential energy, is:

Accepted Answer

A)   300 J
B)   710 J
C)   850 J
D)   7000 J
E)   8400 JF) A) and B)
G) All of the above

Question 7

Objects A and B interact with each other via both conservative and nonconservative forces. Let KA and KB be the kinetic energies, U be the potential energy, and Eint be the internal energy. If no external agent does work on the objects then:

Accepted Answer

A)   KA + U is conserved
B)   KA + U + Eint is conserved
C)   KA + KB + Eint is conserved
D)   KA + KB + U is conserved
E)   KA + KB + U + Eint is conservedF) None of the above
G) C) and D)

Question 8

The diagram shows a plot of the potential energy as a function of x for a particle moving along the x axis. The points of neutral equilibrium are:

Accepted Answer

A)   only a
B)   only b
C)   only c
D)   only d
E)   b and dF) B) and D)
G) B) and E)

Question 9

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 JF) A) and E)
G) C) and D)

Question 10

A small object of mass m, on the end of a light cord, is held horizontally at a distance r from a fixed support as shown. The object is then released. What is the in the cord when the object is at the lowest point of its swing?

Accepted Answer

A)   mg/2
B)   mg
C)   2 mg
D)   3 mg
E)   mgrF) B) and C)
G) A) and E)

Question 11

A 0.5-kg block slides along a horizontal frictionless surface at 2 m/s. It is brought to rest by compressing a very long spring of spring constant 800 N/m. The maximum spring compression is:

Accepted Answer

A)   0 cm
B)   3 cm
C)   5 cm
D)   80 cm
E)   80 mF) B) and E)
G) None of the above

Question 12

As a particle moves along the x axis it is acted by a conservative force. The potential energy is shown below as a function of the coordinate x of the particle. Rank the labeled regions according to the magnitude of the force, least to greatest.

Accepted Answer

A)   AB, BC, CD
B)   AB, CD, BC
C)   BC, CD, AB
D)   BC, AB, CD
E)   CD, BC, ABF) B) and D)
G) C) and E)

Question 13

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/sF) A) and C)
G) A) and E)

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, 2, 1
E)   2, 1, 3F) C) and E)
G) None of the above

Question 15

The potential energy of a particle moving along the x axis is given by U(x)  = (8.0J/m2) x2 + (2.0J/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 mF) A) and C)
G) A) and B)

Question 16

A block of mass m is initially moving to the right on a horizontal frictionless surface at a speed v. It then compresses a spring of spring constant k. At the instant when the kinetic energy of the block is equal to the potential energy of the spring, the spring is compressed a distance of:

Accepted Answer

A)   2 
C)   (1/4) mv2 
D)   mv2/4k 
E)    " class="answers-bank-image d-inline" rel="preload" >
B)   (1/2) mv2
C)   (1/4) mv2
D)   mv2/4k
E)   2 
C)   (1/4) mv2 
D)   mv2/4k 
E)    " class="answers-bank-image d-inline" rel="preload" >F) A) and B)
G) A) and C)

Question 17

A particle is released from rest at the point x = a and moves along the x axis subject to the potential energy function U(x)  shown. The particle:

Accepted Answer

A)   moves to a point to the left of x = e, stops and remains at rest
B)   moves to a point to x = e, then moves to the left
C)   moves to infinity at varying speed
D)   moves to x = b where it remains at rest
E)   moves to x = e and then to x = d, where it remains at restF) A) and E)
G) B) and D)

Question 18

The diagram shows a plot of the potential energy as a function of x for a particle moving along the x axis. The points of stable equilibrium are:

Accepted Answer

A)   only a
B)   only b
C)   only c
D)   only d
E)   b and dF) A) and B)
G) A) and C)

Question 19

The long pendulum shown is drawn aside until the ball has risen 0.5 m. It is then given an initial speed of 3.0 m/s.. The speed of the ball at its lowest position is:

Accepted Answer

A)   zero
B)   0.89 m/s
C)   3.1 m/s
D)   3.7 m/s
E)   4.3 m/sF) A) and B)
G) B) and E)

Question 20

A simple pendulum consists of a 2.0 kg mass attached to a string. It is released from rest at X as shown. Its speed at the lowest point Y is:

Accepted Answer

A)   0.90 m/s
B)   
C)   3.6 m/s
D)   6.0 m/s
E)   36 m/sF) A) and B)
G) A) and C)

Exam 8: Potential Energy and Conservation of Energy

As a particle moves along the x axis it is acted by a conservative force. The potential energy is shown below as a function of the coordinate x of the particle. Rank the labeled regions according to the magnitude of the force, least to greatest.

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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:

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A block of mass m is initially moving to the right on a horizontal frictionless surface at a speed v. It then compresses a spring of spring constant k. At the instant when the kinetic energy of the block is equal to the potential energy of the spring, the spring is compressed a distance of:

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The sum of the kinetic and potential energies of a system of objects is conserved:

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A projectile of mass 0.50 kg is fired with an initial speed of 10 m/s at an angle of 60 ° above the horizontal. The potential energy of the projectile-Earth system when the projectile is at its highest point (relative to the potential energy when the projectile is at ground level) is:

Correct AnswerverifiedShow Answer

A particle is released from rest at the point x = a and moves along the x axis subject to the potential energy function U(x) shown. The particle:

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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 of one atom exerts on the other is:

Correct AnswerverifiedShow Answer

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:

Correct AnswerverifiedShow Answer

Objects A and B interact with each other via both conservative and nonconservative forces. Let KA and KB be the kinetic energies, U be the potential energy, and Eint be the internal energy. If no external agent does work on the objects then:

Correct AnswerverifiedShow Answer

A simple pendulum consists of a 2.0 kg mass attached to a string. It is released from rest at X as shown. Its speed at the lowest point Y is:

Correct AnswerverifiedShow Answer

The diagram shows a plot of the potential energy as a function of x for a particle moving along the x axis. The points of stable equilibrium are:

Correct AnswerverifiedShow Answer

A golf ball is struck by a golf club and falls on a green eight feet above the tee. The potential energy of the Earth-ball system is greatest:

Correct AnswerverifiedShow Answer

A small object of mass m, on the end of a light cord, is held horizontally at a distance r from a fixed support as shown. The object is then released. What is the in the cord when the object is at the lowest point of its swing?

Correct AnswerverifiedShow Answer

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

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The diagram shows a plot of the potential energy as a function of x for a particle moving along the x axis. The points of neutral equilibrium are:

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A 0.5-kg block slides along a horizontal frictionless surface at 2 m/s. It is brought to rest by compressing a very long spring of spring constant 800 N/m. The maximum spring compression is:

Correct AnswerverifiedShow Answer

The long pendulum shown is drawn aside until the ball has risen 0.5 m. It is then given an initial speed of 3.0 m/s.. The speed of the ball at its lowest position is:

Correct AnswerverifiedShow Answer

The diagram shows a plot of the potential energy as a function of x for a particle moving along the x axis. The points of unstable equilibrium are:

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A 700-N man jumps out of a window into a fire net 10 m below. The net stretches 2 m before bringing the man to rest and tossing him back into the air. The maximum potential energy of the net, compared to it's unstretched potential energy, is:

Correct AnswerverifiedShow Answer

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.

Correct AnswerverifiedShow Answer

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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 of one atom exerts on the other is:

Correct Answer
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Objects A and B interact with each other via both conservative and nonconservative forces. Let K_A and K_B be the kinetic energies, U be the potential energy, and E_int be the internal energy. If no external agent does work on the objects then:

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

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