Which of these does not result in the acceleration of an object?
a.) a decrease in speed
b.) an increase in speed
c.) a change in direction
d.) maintaining a constant velocity

The correct answer is D.

Acceleration is defined as a change in velocity. A and B clearly demonstrate a change in velocity so are eliminated. And since velocity is a vector quantity that consists of both magnitude and direction, C is also eliminated because it has a change in direction.

Let me know if you have any questions.

I guess the correct answer is the first one.

Pulley: A member of the lever family, a pulley is a simple machine that uses a grooved wheel and a rope to move a load.