# Rotational Velocity

1. Feb 9, 2009

### samprots

1. The problem statement, all variables and given/known data
A wheel has a rotational velocity of 14 rad/s clockwise you place your hand against the wheel and the friction between your hand and the rim stops it
a) If it takes 5s to stop the wheel what is its rotational acceleration
b)How far does the wheel rotate while slowing to a stop?

2. Relevant equations

3. The attempt at a solution
I got A very easy just taking 14/5 but am struggling with part B
Here is what I have so far, and I know its wrong but cannot figure it out
any help would be greatly appreciated

W.t+1/2t(squared)

I have 14*5+1/2*2.8(squared)
70+3.92=73.92

Any help would be greatly appreciated again thanks

2. Feb 9, 2009

3. Feb 9, 2009

### samprots

Bump, any clarification that can be done on my part?

4. Feb 9, 2009

### samprots

Wow thanks for the help, your all so great!

5. Feb 10, 2009

### hage567

Is this supposed to be an equation? Write the whole thing out. Anyway, this equation isn't even correct. You left out a variable. Go back to your textbook and look it up again.

Even if this was the right equation, you've messed up the calculation. t is not "2.8". Did you try to see if your units worked out properly? If they don't, then that's an indication you are doing something wrong.

Instead of bumping your thread every 20 minutes, try spending the time working on figuring out what's wrong yourself. A careful look at the textbook should have at least made you notice something was wrong with your equation.

Was that helpful enough for you?