Answer to Question #288951 in Physics for mary

Question

1. Several environmental scientists are monitoring the movement of a cheetah on an Ethiopian plain. They find that at t = 5 min, the cheetah is traveling at 5 m/s due west. At t = 15 min, it is moving at 12 m/s toward the west, while at t = 30 min it is moving at 2 m/s toward the east. If we call western movement positive, when is the cheetah’s speed negative? A) During the entire interval from t = 15 to t = 30 min B) Only during part of the interval from t = 15 to t = 30 min C) During at least part of the interval from t = 15 to t = 30 min, and possibly at other times D) Never, since speed is not a vector quantity

Answer 1

The cheetah's velocity is negative when it moves toward the east, or at t=30 min and after.

However, the speed is a scalar quantity and it does not have direction, so, it has only magnitude, which is positive.

Thus, the correct answer is D: Never, since speed is not a vector quantity.