Question

The graph (Fig) below describes the motion of a ball rebounding from a horizontal surface being released from a point above the surface. Assume the ball collides each time with the floor inelastically. The quantity represented on the y-axis is the ball's (take upward direction as positive)

• A. Displacement
• B. Velocity
• C. Acceleration
• D. Momentum

Answer 1

The correct option is A Displacement

As particle is left, initial momentum and velocity are zero.
Hence given graph cannot be of velocity or momentum.
As acceleration of body is constant ( acceleration due to gravity)
Hence given graph cannot be of acceleration.

Given graph is of displacement:
For a body thrown up, its displacement is given as $S=ut-\frac{1}{2}g{t}^2$.
So it will rebound to less height every time as shown in the graph.
$t_1,t_2,t_3$ ​ are the instants when the ball collides with ground. Here slope of the s−t graph is suddenly changing from negative to positive. It means velocity before collision is negative (downwards) and after collision is positive (upwards).