# Energy Problems

1. Jan 21, 2010

### bradefeld

1. The problem statement, all variables and given/known data
Initially, a 10 kg block is sliding along the floor at a speed of 5 m/x. The coefficient of friction between the block and the floor is 0.5.

What are the KE, PE and total energies of the block after sliding 2.0 m?
What is the block's speed after sliding 2.0 m?

I don't recall how to apply friction to velocity in order to do the KE equation.

2. Relevant equations

3. The attempt at a solution

2. Jan 21, 2010

### Yitzach

$$f_k=\mu_kn$$
$$f_k$$ is the force of kinetic friction. This number will be very important to you proceeding.
$$\mu_k$$ is the coefficient of kinetic friction
n is the normal force

3. Jan 21, 2010

### bradefeld

Yes, we found the friction force. Now how do we use that amount to figure out the energies and the final velocity?

4. Jan 21, 2010

### tiny-tim

Welcome to PF!

Yitzach, you must stop making these unhelpful comments in homework threads.

Hi bradefeld! Welcome to PF!

You'll need to use the work-energy theorem … work done = change in energy.

So … what is the work done after 2.0 m ?

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook