# Problem with Energy Dissipation

Tags:
1. Apr 30, 2017

### sojo

1. The problem statement, all variables and given/known data

A 4.70-kg steel ball is dropped from a height of 11.0 m into a box of sand and sinks 0.500 m into the sand before stopping. How much energy is dissipated through the interaction with the sand? Express answer using three significant digits.
2. Relevant equations
Potential Energy = mhg
Mechanical Energy = (1/2)mv^2

3. The attempt at a solution
I thought that the energy dissipated would be equal to the potential energy at the start of the problem. So I found the initial potential energy with the equation mgh = (4.7)(11)(9.8) = 507 However, I submitted this answer and the program said it was incorrect.

2. May 1, 2017

### TSny

Hello. Welcome to PF!

What is the total distance the ball travels vertically?

3. May 1, 2017

### sojo

I guess it falls 11.5 m including the distance in the sand. Do I include the distance in the sand?

4. May 1, 2017

### TSny

Is there any change in gravitational potential energy when the ball moves 0.5 m downward in the sand?

5. May 1, 2017

### sojo

Yeah there is. That makes a lot of sense. Thanks for your help!

6. May 1, 2017

### TSny

OK. Hope it works out now.