# Bodies with potential energy

• aurao2003
In summary, the conversation discusses a problem involving a rubber ball dropped from a height of 2 meters onto flat ground. The first part asks for the time it takes for the ball to hit the ground, which can be solved using the equation of motion. The second part involves the ball losing 10% of its kinetic energy at each bounce and the question asks for the time it takes for the ball to come to rest. The solution involves finding the initial velocity after each bounce and using that to find the time between bounces, which forms a geometric progression.

## Homework Statement

Hi
I am struggling with this question. It goes like this:

A rubber ball is dropped on to flat ground from a height of 2m.
(a) Calculate how long it takes for the ball to first hit the ground.

(b)The ball loses 10% of its kinetic energy at each bounce. Calculate the time taken for the ball to come to rest.

I am able to solve the first part using equation of motion.
S=UT +0.5aT^2

I am not sure of the second part.

## The Attempt at a Solution

hi aurao2003!
aurao2003 said:
(b)The ball loses 10% of its kinetic energy at each bounce. Calculate the time taken for the ball to come to rest.

find the initial velocity, immediately after the first bounce, and use that to find the time between the first and second bounces

then do the same for all the bounces, and add them …

what do you get?

tiny-tim said:
hi aurao2003!

find the initial velocity, immediately after the first bounce, and use that to find the time between the first and second bounces

then do the same for all the bounces, and add them …

what do you get?

It seems to be forming a geometric progression. Is that right?

s'right!

Cheers!

## What is potential energy?

Potential energy is the energy an object possesses due to its position or configuration in a force field. It is a type of stored energy that can be released to do work.

## How is potential energy different from kinetic energy?

Potential energy is the energy an object has due to its position while kinetic energy is the energy an object has due to its motion. Potential energy can be converted into kinetic energy and vice versa.

## What are some examples of bodies with potential energy?

Some examples of bodies with potential energy include a book sitting on a shelf, a stretched rubber band, a compressed spring, and a pendulum at its highest point.

## How is potential energy calculated?

The formula for potential energy is PE = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object relative to a reference point.

## Can potential energy be negative?

Yes, potential energy can be negative. This occurs when the reference point is set at a height higher than the object, resulting in a negative value for h in the potential energy formula.