# Angular Acceleration

1. Nov 16, 2009

### Devin Longo

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

A cyclist starts from rest and pedals so that the wheels make 8.5 revolutions in the first 4.5 s. What is the angular acceleration of the wheels (assumed constant)?

2. Relevant equations

$$\alpha$$ = $$\Delta$$$$\omega$$/ $$\Delta$$t

3. The attempt at a solution

I converted 8.5 to radians and divided by 4.5. BUT I CANT GET THE RIGHT ANSWER!!

2. Nov 16, 2009

### rl.bhat

Use the formula
θ = ωο*t + 1/2*α*t^2 and find α.

3. Nov 16, 2009

### Devin Longo

So, I do that and I get .839. I kept 8.5 as my theta. It still isn't right. What could I be doing wrong?

4. Nov 16, 2009

### rl.bhat

No. The angular displacement θ = 2*π*n, where n is the number of revolutions per second.