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Quiz Feedback | Introductory Physics I with Laboratory
Feedback — Potential Energy II
You submitted this quiz on Fri 5 Jul 2013 9:38 AM PDT (UTC -0700). You got a
score of 5.00 out of 10.00. You can attempt again, if you'd like.
Some questions provided by Matter and Interactions (3rd. Ed.), R. Chabay & B. Sherwood.
Copyright (2010, John Wiley & Sons). This material is used by permission of John Wiley &
Sons, Inc.
Question 1
3
The radius of Mercury (from the center to just above the atmosphere) is 2440 km (2440 × 10
24
m), and its mass is 0.3 × 10
kg. An object is launched straight up from just above the
atmosphere of Mercury.
What initial speed is needed so that when the object is far from Mercury its final speed is 1000
m/s?
Answer in m/s.
You entered:
3924.49
Your Answer
3924.49
Score

Total
Explanation
0.00
0.00 / 1.00
Question Explanation
Answer : [4170,4190]
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Question 2
For the system described in the previous question...
What initial speed is needed so that when the object is far from Mercury its final speed is 0 m/s?
(This is called the "escape speed.")
Answer in m/s.
You entered:
4049.89
Your Answer
Score
4049.89

Total
Explanation
1.00
1.00 / 1.00
Question Explanation
Answer : [4040,4070]
Question 3
The diagram below is a graph of the energy of a system of a planet interacting with a star. The
gravitational potential energy Ug is shown as the thick curve, and plotted along the vertical axis
are various values of K
+ Ug .
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Suppose that energy of the system, K
+ Ug ,
is equal to A. Which of the following statements
are true?
Your Answer
The kinetic energy of the system is greater when the distance
Score

0.17

0.17
The planet will escape.

0.17
The system is a bound system; the planet can never escape.

0.17
The potential energy of the system decreases as the planet

0.17

0.17
Explanation
between the star and planet is r1 than when the distance
between the two bodies is r2.
When the separation between the two bodies is r2, the kinetic
energy of the system is (B - C).
moves from r1 to r2.
When the separation between the two bodies is r2, the kinetic
energy of the system is (A - B).
Total
1.00 /
1.00
Question Explanation
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Answer :
-The kinetic energy of the system is greater when the distance between the star and planet is
r1 than when the distance between the two bodies is r2.
-When the separation between the two bodies is r2, the kinetic energy of the system is (A - B).
-The system is a bound system; the planet can never escape.
Question 4
For the system described in the previous question...
Suppose instead that the energy, K
+ Ug ,
is equal to B. Which of the following statements are
true?
Your Answer
When the separation between the planet and star is r2, the
kinetic energy of the system is zero.
Score

0.25
The planet and star cannot get farther apart than r2.

0.25
This is not a bound system; the planet can escape.

0.25

0.25
When the separation between the planet and star is r2, the
potential energy of the system is zero.
Total
Explanation
1.00 /
1.00
Question Explanation
Answer :
-The planet and star cannot get farther apart than r2.
-When the separation between the planet and star is r2, the kinetic energy of the system is
zero.
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Question 5
The diagram above shows the path of a comet orbiting a star. You will be asked to rank order
various quantities in terms of their values at the locations marked on the path, with the largest
first. You can use the symbols ">" and "=".
For example, if you were asked to rank order the locations in terms of their distance from the
star, largest first, you would type:
"A>B>C>D>E"
Note: Do not include spaces. Otherwise your answer may be graded improperly.
Rank order the locations on the path in terms of the magnitude of the comet's momentum at
each location, starting with the location where the magnitude of the momentum is the largest:
You entered:
A=B=C=D=E
Your Answer
A=B=C=D=E
Score

Total
Explanation
0.00
0.00 / 1.00
Question Explanation
Answer : E>D>C>B>A
Question 6
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For the system described in the previous question...
Rank order the locations on the path in terms of the comet's kinetic energy at each location,
starting with the location where the kinetic energy is the largest:
You entered:
A>B>C>D>E
Your Answer
A>B>C>D>E
Score

Total
Explanation
0.00
0.00 / 1.00
Question Explanation
Answer : E>D>C>B>A
Question 7
For the system described in the previous question...
Consider the system of the comet plus the star.
Which of the following statements are correct?
Your Answer
Score
As the comet slows down, the kinetic energy of the system
decreases.

0.20
External work must be done on the system to speed up the

0.20
As the comet slows down, energy is lost from the system.

0.20
As the kinetic energy of the system increases, the

0.20
Explanation
comet.
gravitational potential energy of the system decreases.
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As the comet's kinetic energy increases, the gravitational

0.20
potential energy of the system also increases.
Total
1.00 /
1.00
Question Explanation
Answer :
-As the kinetic energy of the system increases, the gravitational potential energy of the system
decreases.
-As the comet slows down, the kinetic energy of the system decreases.
Question 8
For the system described in the previous question...
Still Consider the system of the comet plus the star.
Which of the following statements are also correct?
Your Answer
Along this path the gravitational potential energy of the
Score

0.20

0.20

0.20

0.20

0.20
Explanation
system is never zero.
The sum of the kinetic energy of the system plus the
gravitational potential energy of the system is a positive number.
The sum of the kinetic energy of the system plus the
gravitational potential energy of the system is the same at every
location along this path.
At every location along the comet's path the gravitational
potential energy of the system is negative.
The gravitational potential energy of the system is inversely
proportional to the square of the distance between the comet
and star.
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Total
1.00 /
1.00
Question Explanation
Answer :
-At every location along the comet's path the gravitational potential energy of the system is
negative.
-Along this path the gravitational potential energy of the system is never zero.
-The sum of the kinetic energy of the system plus the gravitational potential energy of the
system is the same at every location along this path.
Question 9
For the system described in the previous question...
Rank order the locations on the path in terms of the potential energy of the system at each
location, largest first. (Remember that -3 > -5).
Note: Do not include spaces in your answer. Otherwise your answer may be graded improperly.
You entered:
E>D>C>B>A
Your Answer
E>D>C>B>A
Score

Total
Explanation
0.00
0.00 / 1.00
Question Explanation
Answer : A>B>C>D>E
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Question 10
Consider an isolated system, by which we mean a system free of external forces. If the sum of
the particle energies in the system increases by 150 J, what must have been the change in the
system's potential energy, ΔU ?
Answer in J.
You entered:
0
Your Answer
0
Score

Total
Explanation
0.00
0.00 / 1.00
Question Explanation
Answer : -150
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