Suggest a suitable physical situation for each of the following graphs.

(a) The given position-time graph shows that initially a body was at rest. Gradually, its velocity increases with time and attains an instantaneous constant value. Then, the velocity reduces to zero with an increase in time. Then, its velocity increases with time in the opposite direction and acquires a constant value.
A physical situation analogous to this graph arises when a football (initially kept at rest) is kicked and gets rebound from a rigid wall so that its speed gets reduced. Then, it passes from the player who has kicked it and ultimately gets stopped after sometime. 
(b) In the given velocity-time graph, the sign of velocity changes and its magnitude decreases with a passage of time. A similar situation arises when a ball is dropped on the hard floor from a height. It strikes the floor with some velocity and upon rebound, its velocity decreases by a factor. This continues till the velocity of the ball eventually becomes zero.

(c) The given acceleration-time graph reveals that initially the body is moving with a certain uniform velocity. Its acceleration increases for a short interval of time, which again drops to zero. This indicates that the body again starts moving with the same constant velocity. A similar physical situation arises when a hammer moving with a uniform velocity strikes a nail.