# Homework Help: Calculate energy lost to a rough surface

1. Apr 29, 2014

### Toliver96

1. The problem statement, all variables and given/known data
A block of mass 2kg, moving at velocity 2.68 m/s, slides across a rough 3m surface with a coefficient of kinetic friction of .4. Calculate the energy lost to the 3m rough surface.
M=2kg
uK=.4
V=2.68 m/s
D=3m

2. Relevant equations
1/2mv^2
uK*Fn*D

3. The attempt at a solution
I used the kinetic energy equation of 1/2mv^2 to get 7.18J. Then I did uK*Fn*D to get 24J, where Fn is normal force and Gravity = 10m/s^2. I have no idea where to go from here.

Last edited: Apr 29, 2014
2. Apr 29, 2014

### SammyS

Staff Emeritus
What does that 24 J represent ?

3. Apr 29, 2014

### Toliver96

It is supposed to be Jules, but I'm not sure if that's correct.

4. Apr 29, 2014

### SammyS

Staff Emeritus
The units are Joules, but what does the 24 Joules represent?

5. Apr 29, 2014

### Toliver96

The energy lost to the rough surface, but how can it lose more energy than what it has?

6. Apr 29, 2014

### SammyS

Staff Emeritus
What happens to the block when the energy lost is equal to the initial Kinetic Energy ?

7. Apr 29, 2014

### Toliver96

So the block will stop then, right?

8. Apr 29, 2014

### SammyS

Staff Emeritus
Right.