What change continuously in uniform circular motion?

A ball hits a wall horizontally at 8.0 m/s^-1. It rebounds horizontally at 4.4 m s^-1. The ball is in contact with the wall for 0.040 s. What is the acceleration of the ball?

What remain constant in uniform curcular motion?

State whether the following statement is true of false:

Earth moves round the sun with non- uniform velocity.

A body goes round the sun with constant speed in a circular orbit. Is the motion uniform or accelerated?