Question

A ball is dropped on a floor and bounces back to a height somewhat less than the original height. The curve which depicts its motion correctly about $y$ and $t$ is

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

When a ball is dropped on a floor then
$y=\frac{1}{2}g{t}^2\dots \left(i\right)$
So, the graph between $yandt$ is a parabola. Here $y$ decrease as time decrease. When the ball is bounces back then
$y=ut-\frac{1}{2}g{t}^2\dots \left(ii\right)$
Eq. (ii) is also the form of a general equation of parabola so the graph between $yandt$ will be a parabola. Here $y$ increases when the time increases. Hence, the required graph between $yandt$ is shown in the figure.