What do you mean by constant acceleration?

Hint – In this question use the concept that uniform acceleration is also called constant acceleration. The rate change of velocity with respect to time is termed as acceleration so if this rate change is constant then simply it is a constant or uniform acceleration. This will help getting the answer.

Complete step-by-step answer:

Uniform acceleration
Uniform or constant acceleration is a type of motion in which an object's velocity varies by the same amount in any equivalent period of time.
A widely cited example of uniform acceleration in a uniform gravitational field is that of an object in free fall. In the absence of resistance to motion, the acceleration of a falling body depends only on the gravitational field strength (g = 9.8 m/${s^2}$), (also called acceleration due to gravity). By Newton’s second law the force ${F_g}$ acting on a body is given by:
$ \Rightarrow {F_g} = mg$, where m = mass of the object which is falling and g = acceleration due to gravity.
So this is the required answer.

Note – Constant circular motion can be subjected to a horizontal direction of motion only, as in this case there may be a case that velocity is not changing for example a car moving with a constant speed on a straight road. However in case of circular motion there cannot be constant acceleration as in this motion the velocity is always tangential and tangent at every point is unique, so there is a rate change of velocity