A strobe photograph of a car moving along a straight road shows the interval between each successive image to be diminishing.If the direction of motion of the car is taken as positive,which of the following is/are negative?
A)the speed of the car
B)the average velocity of the car
C)the average acceleration of the car
D)all of the above

Question

Quizplus · Accepted Answer

The diminishing interval between each successive image indicates that the car is decelerating. If the direction of motion is positive, a deceleration (or negative acceleration) means the car is slowing down, hence the average acceleration is negative. Speed, being a scalar, cannot be negative, and the average velocity, which is direction-dependent, is positive since the car continues to move in the positive direction despite slowing down.

A Strobe Photograph of a Car Moving Along a Straight