Physics SAT Subject Test

Robert Jansen, Greg Young

Chapter 7

Energy, Work, and Power - all with Video Answers

Educators

Chapter Questions

Problem 1

In order for an object to have potential energy capable of doing work
(A) the potential energy must have a positive value
(B) the object must have energy associated with its position
(C) the object must have kinetic energy
(D) the object must be in a position where it can lose its potential energy when
released
(E) the object must be stationary

Vishal Gupta

Vishal Gupta

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Problem 2

Stretching a springa distance of $x$ requires a force of $F$ . In the process, potential
energy, $U,$ is stored in the spring. How much force is required to stretch the spring
a distance of $2 x,$ and what potential energy is stored in the spring as a result?
(A) $F$ and 2$U$
(B) 2$F$ and 2$U$
(C) 2$F$ and 4$U$
(D) 4$F$ and 4$U$
(E) 4$F$ and 8$U$

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Problem 3

The total mechanical energy of a system
(A) always remains constant
(B) is equal to the net work done on a system
(C) is the energy stored in the system
(D) is the kinetic energy of the system
(E) is the sum of the kinetic and potential energies in the system

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Problem 4

A $1,000$ -kilogram satellite completes a uniform circular or bit of radius $8.0 \times 10^{6}$
meters as measured from the center of Earth. The mass of Earth is approximately
$6.0 \times 10^{24}$ kilograms, and the universal gravity constant is approximately $7.0 \times$
$10^{-11} \mathrm{N} \cdot \mathrm{m}^{2} / \mathrm{kg}^{2} .$ Determine the work done by gravity as the satellite completes
one full orbit around Earth.
(A) Zero
(B) $5.3 \times 10^{10} \mathrm{J}$
(C) $8.0 \times 10^{10} \mathrm{J}$
(D) $3.3 \times 10^{11} \mathrm{J}$
(E) $5.0 \times 10^{11} \mathrm{J}$

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Problem 5

The force-displacement graph above depicts the force applied to a 2.0-kilogram
mass as it is displaced 10 meters. The initial speed of the mass is 5.0 meters per
second. The final speed of the mass is most nearly
(A) 7 $\mathrm{m} / \mathrm{s}$
(B) 10 $\mathrm{m} / \mathrm{s}$
(C) 12 $\mathrm{m} / \mathrm{s}$
(D) 16 $\mathrm{m} / \mathrm{s}$
(E) 20 $\mathrm{m} / \mathrm{s}$

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Problem 6

Questions $6-7$
The diagram below depicts a 3.0 -newton block sliding down a frictionless $30^{\circ}$ incline. The mass is initially at rest at the top of the incline.
The work done by gravity is
(A) 15 $\mathrm{J}$
(B) 30 $\mathrm{J}$
(C) 60 $\mathrm{J}$
(D) 150 $\mathrm{J}$
(E) 300 $\mathrm{J}$

Vishal Gupta

Numerade Educator

Problem 7

Questions $6-7$
The diagram below depicts a 3.0 -newton block sliding down a frictionless $30^{\circ}$ incline. The mass is initially at rest at the top of the incline.
The final speed of the mass when it reaches the bottom of the incline is most
nearly
(A) 1.0 $\mathrm{m} / \mathrm{s}$
(B) 1.4 $\mathrm{m} / \mathrm{s}$
(C) 5.0 $\mathrm{m} / \mathrm{s}$
(D) 10 $\mathrm{m} / \mathrm{s}$
(E) 100 $\mathrm{m} / \mathrm{s}$

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Problem 8

You want to lift an object 1 meter. Pushing the object up a $30^{\circ}$ incline takes twice
as long as lifting it straight up. When you use the incline, compared to lifting it
straight up, you do
(A) half the work and use half the power
(B) half the work and use the same power
(C) the same work and use half the power
(D) the same work and use the same power
(E) twice the work and use half the power

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Problem 9

A rock of mass 5.0 kilograms is dropped from a height of 10 meters. What is the
kinetic energy of the rock when it reaches the halfway point of its descent?
(A) 15 $\mathrm{J}$
(B) 25 $\mathrm{J}$
(C) 50 $\mathrm{J}$
(D) 250 $\mathrm{J}$
(E) 500 $\mathrm{J}$

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Problem 10

As shown in the diagram above, pendulum swings from point $A$ to point $E .$ Identify
the statement below that is NOT correct.
(A) The energy at both points $A$ and $E$ is entirely potential energy.
(B) The total energy is decreasing from $A$ to $C$ and is increasing from $C$ to $E$
(C) The kinetic energy is greatest at point $C .$
(D) The total energy at point $A$ equals the total energy at point $C .$
(E) Potential energy is decreasing and kinetic energy is increasing from point $A$ to
C.

Ankit Pandey

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