PSAT Math Multiple-Choice Question 104: Answer and Explanation

Question: 104

The formula F = ma is used to calculate the force on an object with a mass, m, and an acceleration, a. Based on this formula, what is the acceleration, a, in terms of F and m?

• A. a = Fm
• B. a = F + m
• C.
• D.

Correct Answer: C

Explanation:

C

The question asks for an equation in terms of a specific variable. There are two good ways to solve. One is to solve for a. To begin to isolate a, divide both sides of the equation by m to get . Another option is to plug in. Choose easy numbers that fulfill the equation F = ma, such as m = 2, a = 3, and F = 6. Now plug m = 2, a = 3, and F = 6 into the answer choices to see which one contains a true equation. Choice (A) becomes 3 = (6)(2). This is not true, so eliminate (A). Choice (B) becomes 3 = 6 + 2. Eliminate (B). Choice (C) becomes . This is true, so keep (C), but check (D) just in case. Choice (D) becomes , which is not true, so eliminate (D). With either strategy, the correct answer is (C).