Unit: Motion in a Plane
Year: 1997 Question#: 65
Question: The diagram below represents the path of a planet in an elliptical orbit around the Sun.
As the planet moves from point A to point B, what changes occur in its speed and kinetic energy?
(1 ) Both speed and kinetic energy decrease.
(2 ) Both speed and kinetic energy increase.
(3 ) Speed decreases and kinetic energy increases.
(4 ) Speed increases and kinetic energy decreases.
What is this question really asking?
Explanation by: Erika M.
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Answer 1
Both speed and kinetic energy decrease.
CORRECT
As the planet moves farther away, the attractive gravitational force slows the planet down.
As the velocity decreases, so does the kinetic energy.
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Answer 2
Both the speed and kinetic energy increase
INCORRECT
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Answer 3
Speed decreases and kinetic energy increases.
INCORRECT
As the velocity increases, so does the kinetic energy. They will always be affected
in the same manner, so it is impossible for one to decrease and the other to increase.return to top
Answer 4
Speed increases and kinetic energy decreases.
INCORRECT
As the velocity increases, so does the kinetic energy. They will always be affected
in the same manner, so it is impossible for one to decrease and the other to increase.return to top
What's this question really asking?
This is asking if you understand the forces on an orbiting planet. return to top
