SAT Subject Physics Practice Question 386: Answer and Explanation

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Question: 386

7. A dog walks 120 m due east before turning and running 45 m west. He then turns and trots 40 m due north. After completing his journey, he is 85 m northeast of his home. When he hears his master call him, he runs directly home.

Which part of the trip is a negative vector?

A. The eastward leg
B. The westward leg
C. The northward leg
D. The distance from home
E. The distance to home

Correct Answer: B

Explanation:

The correct answer is (B). When you set the problem into the x, y coordinate system, the negative y axis is the westward direction. Any vector in the western direction is negative.

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