Question

Is it possible for speed to be constant while acceleration is not zero? Give an example of such a situation.

Short answer

Yes, it is possible in the case of uniform circular motion.

Step-by-step solution

Velocity and Acceleration

Keep in mind that speed and velocity are not interchangeable terms. Because velocity is a vector, it has a magnitude as well as a direction. The magnitude element of the velocity is called speed.

The change in velocity over time is referred to as acceleration.

There will be an acceleration if the magnitude (speed) or direction (direction) of the velocity changes.

Example where speed is constant, but acceleration is non-zero

An object traveling in a uniform circular motion would have a constant speed and centripetal acceleration (directed toward the center of the circle). Still, its velocity would not be constant since the object's motion direction is changing.

An item thrown straight up is another example. At the peak of its motion, it would have zero speed (the magnitude of the velocity is 0), but the change in velocity is not zero since the object's motion shifts from upward to downward.

Hence there are cases in which even speed is constant, but acceleration is possible only because of the direction component.