# Angular acceleration of machinery

1. Jul 23, 2008

### Lance WIlliam

A piece of machinery is spinning at 760rpm . When a brake is applied, its rotation rate drops to 480rpm while it turns through 210 revolutions.

What is the magnitude of the angular deceleration?

Eqn I used:$$\omega$$^2=$$\omega$$_0_^2+2$$\alpha$$(change in theta)

I put 480^2=760^2+2(alpha)210

I got 3.79e-3...
Wrong...:(
what did I do wrong? Ithink its the units, they are very confusing.

2. Jul 23, 2008

### cryptoguy

i'd convert the distance to radians, and all the speeds to radians per sec right off the bat. so 760 rpm x 2pi / 60 would give you rad/s for example

3. Jul 23, 2008

Thankyou