Give one example of each type of the following motion:
(a) uniform velocity (b) variable velocity
(c) variable acceleration (d) uniform retardation
(a) uniform velocity - a car travelling with constant speed on a straight road
(b) variable velocity - a car travelling on a circular track
(c) variable acceleration - a car moving on a circular track at variable speed
(d) uniform retardation - a ball thrown upwards from the ground