draw the speed time graph and a velocity time graph for a stone that is thrown vertically upwards,attains the maximum height and then comes down.How will these two be different?(Note:make the graphs before the stone hits the ground and the velocity becomes zero )

A direction is associated with velocity. So, let stone going upward is positive velocity, while stone coming downwards is negative velocity. Speed cannot tell if the stone is going upward or downward. Therefore, we can have negative velocity, but there is no such thing as negative speed.

A speed-time graph will always stay positive, while a velocity-time graph can go negative.

Velocity time graph:

 

 

 

 

Speed time graph: