# Kinetic energy dissipation by friction

1. Feb 17, 2012

### NoobBR

Is the equation right ? How do i solve it ?

Thanks in advance and sorry about my poor english or something else

2. Feb 17, 2012

### Staff: Mentor

Not really. That's not a force equation, but an energy balance one. By setting up such an energy balance equation, you could solve for the distance traveled. But that's not what's asked for.

What's the force of friction?

3. Feb 17, 2012

### vivekrai

It is infact just a Kinematics 1D Problem. The body undergoes a constant retardation due to friction. So just use v = u + at .

4. Feb 17, 2012

### NoobBR

hmm i formulated wrong. If the friction coeficient "u" is a nonlinear function, lets say, u = x^2 how it would be solved ?

5. Feb 17, 2012

### vivekrai

Write force equation and solve the differential Equation.

We'll have $m\cdot \frac{dv}{dt} = \mu mg \implies v dv =k x^2g dx$, Since $\mu = kx^2$

6. Feb 17, 2012

### NoobBR

Thank you very much for the help, you people are right and its a question about aceleration.

Greetz!