# Circular Rotation Question

1. Oct 11, 2004

### pennyfx

A disk of radius .12 m starts accelerating from rest at 8 rad/s^2 At t = 5s

A)What is the Angular Velocity
And makes sense.

B)What is the tangential Accel?The book gave answer of .96 m/s^s Therefor, i assumed that the equation is At = w*r w=omega which is 8 rad/s^2 * .12m = .96 m/s^2

However, later I found an equation for At given as At=dv/dt
What gives? Which equation is correct for Tangential Accel? If they are both correct then how would I use At=dv/dt?

Thanks

2. Oct 11, 2004

### Gopi Prashanth

Both are correct,

Remember dv/dt is nothing but d(r*Av)/dt and since r is constant r*d(Av)/dt
which is nothing but r*w... which was the first equation you used...