SAT Subject Physics Practice Question 20: Answer and Explanation

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Question: 20

11. If the distance between two point particles is doubled, then the gravitational force between them

A. decreases by a factor of 4
B. decreases by a factor of 2
C. increases by a factor of 2
D. increases by a factor of 4
E. Cannot be determined without knowing the masses

Correct Answer: A

Explanation:

Gravitational force obeys an inverse-square law: Fgrav. Therefore, if r increases by a factor of 2, then Fgrav decreases by a factor of 22 = 4.

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