1. Nov 24, 2009

### ntox101

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

A 13-kg block is at rest on a level floor. A 400-gram glob of putty is thrown at the block such that it travels horizontally, hits the block, and sticks to it. The block and putty slide 15cm along the floor. If the coefficient of sliding friction is 0.4, what is the initial speed of the putty?

2. Relevant equations

3. The attempt at a solution

Okay. I am just going to list my calculations to save the stress of learning LaTeX.

We know the initial velocity of the block being hit ($$m_{1}$$) = 0 m/s
With this known, I can find the final velocity after impact.

I have : $$v_{f}$$ = $$\sqrt{2\\mu*g*d}$$ = 1.08 m/s

With now the final velocity after collision, I can calculate the initial velocity of object 2, which is the putty using the equation below.

I have : $$v_{2i}$$ = $$\frac{m_{1} + m_{2}}{m_{2}}$$ * $$v_{f}$$ = 36.18 m/s

2. Nov 24, 2009

### rock.freak667

looks good to me