Homework Help: Acceleration and rotation of centrifuge

1. Oct 7, 2007

aligass2004

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

A typical laboratory centrifuge rotates at 4200 rpm. Test tubes have to be placed into a centrifuge very carefully because of the very large accelerators. a.) What is the acceleration at the end of a test tube that is 11 cm from the axis of rotation? b.) For comparison, what is the magnitude of the acceleration a test tube would experience if dropped from a height of .8 m and stopped in a 1.0 ms long encounter with a hard floor?

2. Relevant equations

a = w^2 r

3. The attempt at a solution

I tried finding the frequency, then using the frequency to find w, which I got to be 439.823. Then I tried finding a, which I got to be 48.381.

2. Oct 7, 2007

PhanthomJay

you forgot to square the w term!

3. Oct 8, 2007

queenyv2005

use T= 2(pi)(r)/v to get the velocity and then use a= v^2/r to get part a

4. Oct 8, 2007

dlgoff

And be sure to include your units.

5. Oct 8, 2007

aligass2004

I did forget to square the w term. I got 21278.87m/s^2 for part a.

6. Oct 8, 2007

aligass2004

For part b, I thought to just use Yf = Yi + Viy(t) + 1/2 (a) (t^2). I got 1.6E6 m/s^2, but it said it was wrong.