SAT Subject Physics Practice Question 253: Answer and Explanation

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Question: 253


The figure above shows the forces acting on an object of mass 2 kg. What is the object’s acceleration?

A. 2 m/s2
B. 2.5 m/s2
C. 3 m/s2
D. 3.5 m/s2
E. 4 m/s2

Correct Answer: B


First, if we add the 2 N force to the left and the 6 N force to the right, we get a 4 N force to the right. Then, adding this to the 3 N force gives us a net force whose magnitude is 5 N (this follows from the famous 3-4-5 right triangle).

Since a = Fnet/m, we get a = (5 N)/(2 kg) = 2.5 m/s2.

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