SAT Subject Physics Practice Question 29: Answer and Explanation

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Question: 29

6. A block of mass 3 kg slides down a frictionless inclined plane of length 6 m and height 4 m. If the block is released from rest at the top of the incline, what is its speed at the bottom?

A. 5 m/s
B. 6 m/s
C. 8 m/s
D. 9 m/s
E. 10 m/s

Correct Answer: D


First, the kinetic energy the block gains is the same as the potential energy it loses, which is mgh. Since this is equal to mv2, we find that v = . Plugging in g = 10 m/s2 and h = 4 m, we get v = ≈ 9 m/s.

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