# Rotational Motion

1. Jun 11, 2008

### islanderman7

1. The problem statement, all variables and given/known data
A tire placed on a balancing machine in a service station starts from rest and turns through 4.9 revolutions in 1.0 s before reaching its final angular speed. Calculate its angular acceleration.

2. Relevant equations
a=w/t

3. The attempt at a solution

a=w/t

What am I doing wrong?

2. Jun 11, 2008

### Dick

It's not a constant angular velocity question. Angular velocity changes with time, so you can't just use a=w/t. You need a formula analogous to s=(1/2)*a*t^2 for linear motion. It looks very similar, just the meaning of the letters changes.

3. Jun 11, 2008

### islanderman7

Okay thanks. I get it now.