A body falling from a height of 10 m rebounds from a hard floor. It loses 20% of its energy in impact.  What is the height to which it would rise after the impact? (Take g = 10 m/s2)

Sure, let's solve this step by step:

Step 1: First, we need to calculate the initial energy of the body when it was at a height of 10m. The potential energy (PE) of an object of mass m at a height h is given by the formula PE = mgh. Here, we don't know the mass of the body, but we don't need it because it will cancel out in our calculations. So, let's just use PE = gh. Substituting g = 10 m/s² and h = 10m, we get PE = 10 * 10 = 100 Joules.

Step 2: The body loses 20% of its energy on impact. So, the energy after impact is 80% of the initial energy. That's 0.8 * 100 = 80 Joules.

Step 3: Now, we need to find the height to which the body would rise after the impact. We know that the energy after impact is equal to the potential energy at the maximum height. So, we can use the formula for potential energy to find this height: PE = gh. Rearranging for h, we get h = PE / g. Substituting PE = 80 Joules and g = 10 m/s², we get h = 80 / 10 = 8m.

So, the body would rise to a height of 8m after the impact.