Consider a rubber ball freely falling from a height h =4.9\: m onto a horizontal elastic plate. Assume that the duration of collision is negligible and the collision with the plate is totally elastic. Then the velocity as a function of time and the height as function of time will be

Option 1)

Option 2)

Option 3)

Option 4)

Answers (1)

As we learnt in

If only conservative forces act on a system, total mechnical energy remains constant -

K+U=E\left ( constant \right )

\Delta K+\Delta U=0

\Delta K=-\Delta U

-

 

 As the ball fall its velocity increases v=\sqrt{2gh}=gt (in\ negative\ direction)

as it reflect after collistion v=v_{0}-gt.

So velocity is linear.

Increasing while going down and decreasing while going up.

h=h_{0} -\frac{1}{2}gt^{2}(going\ down)\ parabolic

h=\frac{1}{2}gt^{2}(going\ up)\ parabolic

So correct graph is 3


Option 1)

This is an incorrect option.

Option 2)

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Option 3)

This is the correct option.

Option 4)

This is an incorrect option.

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