A ball is projected vertically upwards with a velocity v. It comes back to ground in time t. Draw the correct v-t graph taking into consideration the sign convention.

The correct v-t graph taking into consideration the sign convention when a ball is projected vertically upwards with a velocity v and comes back to ground in time t is as follows: - 

 

 

When ball is thrown upwards the velocity is u is given to the ball and the it goes on deacresing while going upward. When ball reaches the maximum height its velocity becomes zero and then again while returning back to the ground the velocity of the ball will goes on increasing.