An elevator platform is going up at a speed $$20$$ $$ms-1$$ and during its upward motion a small ball of $$50$$ g mass falling in downward direction strikes the platform elastically at a speed $$5$$ $$ms-1$$. Find the speed (in$$ $$ms-1) with which the ball rebounds.

Question

Infinity Learn · Accepted Answer

The situation is analysed in the figure. We can consider mass of platform to be very large compared to that of ball, so we have

Velocity of the ball relative to the platform before collision =(20+5) m/s = 25 m/s

Since the collision is elastic, velocity of the ball relative to the platform after the collision = 25 m/s

Therefore , velocity of the ball relative to the ground after the collision = (20+25 ) m/s = 45 m/s (upward)

Collisions

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An elevator platform is going up at a speed 20 ms^-1 and during its upward motion a small ball of 50 g mass falling in downward direction strikes the platform elastically at a speed 5 ms^-1. Find the speed (in ms^-1) with which the ball rebounds.

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Collisions

Remember concepts with our Masterclasses.

An elevator platform is going up at a speed 20 ms-1 and during its upward motion a small ball of 50 g mass falling in downward direction strikes the platform elastically at a speed 5 ms-1. Find the speed (in ms-1) with which the ball rebounds.

Ready to Test Your Skills?

free study material

An elevator platform is going up at a speed 20 ms^-1 and during its upward motion a small ball of 50 g mass falling in downward direction strikes the platform elastically at a speed 5 ms^-1. Find the speed (in ms^-1) with which the ball rebounds.