# Homework Help: Acceleration at the center of circle

1. Feb 6, 2010

### songoku

1. The problem statement, all variables and given/known data
A circle with radius 2 cm rotates at 1000 rpm and the acceleration at the rim is 2 ms-2.
a. What is the acceleration at the center ?
b. What is the acceleration at 1 cm from the center ?

2. Relevant equations

3. The attempt at a solution
a. The acceleration will be zero because the center doesn't move?

b. a = ω2r = 2πf*r = 2π * 1000/60 * 2 x 10-2 = 2/3 π ms-2. Is this right?

Thanks

2. Feb 6, 2010

### willem2

Your answer for a seems to be right. The problem is that the acceleration at the rim of a circle with radius 2 cm that rotates with 1000 rpm is more than 100 times as high as $2 m s^{-2}$
I don't see why the acceleration is given at all in the problem.

For part b you use $\omega$ instead of $\omega^2$ and a radius of 2 cm instead of 1 cm

3. Feb 6, 2010

### songoku

Hi willem

Yeah, my mistake...now I know it's not a good idea to post question at 2 AM..

I also agree that the information given doesn't match the theoretical calculation...something wrong with the question...

Thanks a lot !!