Which example describes constant acceleration due only to a change in direction?
a. increasing speed while traveling around a curve
b. an object at rest
c. traveling around a circular track
d. an object in free fall

c. traveling around a circular track

Explanation:

Acceleration is defined as the rate of change of velocity per unit time:

However, velocity is a vector quantity. This means that acceleration can be due to:

- A change in the speed of an object, or

- A change in the direction of the object

Let's analyze each choice:

a. increasing speed while traveling around a curve  --> in this case, both speed and direction are changing (the direction is changing since the object is moving around a curve), so this is not the correct choice

b. an object at rest  --> here neither the speed nor the direction are changing (in fact, the object is not accelerating), so this is not the correct choice

c. traveling around a circular track  --> here the direction is changing (because the track is circular), while we don't know anything about the speed. If we assume the speed to be constant, then this is the correct choice

d. an object in free fall --> here the speed is changing, while the direction not, so this is not the correct choice