The displacement-time graph for the motion of a ball thrown vertically upwards in the air is shown in figure 1.
As the ball goes higher, its velocity decreases continuously (deceleration) till at time t1, when it reaches the highest point it comes to rest momentarily.
From the instant of throwing vertically upwards to the highest point, the displacement increases and at the highest point the displacement becomes maximum.
The ball then starts falling with increasing velocity (acceleration) and hits the ground at time t2.
During this vertical downward motion, the displacement of the ball decreases gradually and finally becomes zero.
This displacement-time graph is an example of variable velocity.
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