A student lefts a bouncy ball to 1.2m, then releases the ball. The ball bounces back up to 0.86m. Construct an explanation as to what happened to the energy.

the decrease in energy is due to a transformational in internal energy of the body in the rebound.

Explanation:

For this exercise we can calculate the initial and final mechanical energy

        Em₀ = U = m g y₁

        = U = m g y₂

we look for the variation of the energy

       ΔEm = Em_{f} - Em₀

       ΔEm = m g (y_{f} -y₀)

       ΔEm = m g (0.86 -1.2)

       ΔEm = -3.332 m

We can see that there is a decrease in mechanical energy, this is transformed into internal energy of the ball during the impact with the ground, this energy can be formed by several factors such as a part of the friction with the surface, an increase in body temperature or a deformation of the body; there may be a contribution from several of these factors.

In conclusion the decrease in energy is due to a transformational in internal energy of the body in the rebound.

Please find the answer in the explanation

Explanation:

Given that a student lefts a bouncy ball to 1.2m, then releases the ball. The ball bounces back up to 0.86m. To Construct an explanation as to what happened to the energy, let first consider the difference in the two height of the ball.

The initial height = 1.2 metres

Final height = 0.86 metres

There is a loss in elastic potential energy of the ball. And the loss energy is due to the difference in the height of the ball under the gravity.

The loss in elastic potential energy is being converted to the gravitational potential energy.