Question

If a ball is dropped from a height H above the ground, then which of the following is the correct graph for total energy(TE) vs height from the ground(h)?

• A.
• B.
• C.
• D.

Answer 1

The correct option is

A

According to the law of conservation of energy, at all positions, the total energy (kinetic energy + potential energy) is constant.
When the object is at height H, its potential energy = mgH
and its kinetic energy = 0 (the body is in rest).
When the body starts falling, its potential energy decreases as the height decreases and its kinetic energy ($\frac{1}{2}m{v}^2$) increases as its velocity increases.
But total energy i.e, ($mgH+0$) at the top and ($0+\frac{1}{2}m{v}^2$) at the bottom just before striking the ground is equal.