Question

An inelastic ball is dropped from a height of $100cm$. Due to collision with the earth $20$ of its energy is lost. To what height will the ball rise?

• A. $80cm$
• B. $40cm$
• C. $60cm$
• D. $20cm$

Answer 1

The correct option is A $80cm$

We can think it very easily by law of conservation of mechanical energy,

When it has 100% of energy it's total energy was equal to potential energy of it at height of 100cm

So when it has 80% of energy it can reach to a maximum height of 80cm because, at maximum height v=0