question_answer 48)

  Draw a velocity versus time graph of a stone thrown vertically upwards and then coming downwards after attaining the maximum height.

Answer:

  When a stone is thrown vertically upwards, it has some initial velocity (let u). As the stone goes its velocity goes on decreasing (it is moving against the gravity) and at the highest point i.e., maximum height) its velocity become zero. Let the stone takes time 'f second to reach at the highest point. After that stone begins to fall (with zero initial velocity) and its velocity goes on increasing (since it is moving with the gravity) and it reaches its initial point of projection with the velocity v in the same time (with which it was thrown), So,

Velocity	u	0	-u
Time	0	t	2t

Here, we have taken -u because in the upward motion velocity of stone is in upward direction and in the downward motion, the velocity is in downward direction. The velocity-time graph for the whole journey is shown below