Question

A ball is gently dropped from a height of 20 m onto a hard surface where it make an elastic collision. If frictional losses are very small, it returns to its original height and continues to bounce up and down.
1) Show that the speed of the ball just before hits the ground is 20m/s (g=10m/s2)​

Answer 1

Answer:

When a ball is dropped from a height 'h' to the ground, potential energy is completely converted into kinetic energy,

  ie,   mgh=1/2mv²

      ∴ v=√2gh

           =√2×10×20

           =√400

         v=20 m/s     Hence, Proved

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