# Rotation of Rigid Bodies- mastering physics 9.72

1. Dec 6, 2005

### wku_tops

The motor of a table saw is rotating at 3450 rev/min. A pulley attached to the motor shaft drives a second pulley of half the diameter by means of a V-belt. A circular saw blade of diameter 0.208 m is mounted on the same rotating shaft as the second pulley.
PART A: The operator is careless and the blade catches and throws back a small piece of wood. This piece of wood moves with linear speed equal to the tangential speed of the rim of the blade. What is this speed?
PART B:Calculate the radial acceleration of points on the outer edge of the blade to see why sawdust doesn't stick to its teeth.

I converted 3450 rpm to 361.283 rads/s. I know that v=rw, but how do I calculate this with out the radius being given?

2. Dec 6, 2005

### dicerandom

Well they gave you the diameter of the saw blade, so you can divide that by two to get its radius. There's an additional step though, you need to take account of the fact that the shaft which is driving the blade is rotating at a different rate than the shaft which is connected to the motor.

3. Dec 6, 2005

### wku_tops

Is the second shaft rotating twice as fast since its on a belt half the diameter of the first?

4. Dec 6, 2005

### wku_tops

Got It. Thanks.