# Angular Speed Between 2 rims attached by a belt

1. Apr 6, 2010

### dimmermanj

So i'm new to the Physics Forums and am looking for some help on this problem:

Wheel A of radius r=10cm is coupled by belt B to wheel C with radius R=25cm.
the angular speed of wheel A is increased from rest at a constant rate of 1.6 rad/s^2.
Find the time needed for wheel C to reach an angular speed of 100 rev/min, assuming the belt does not slip (hint: the linear speeds of the two rims must be equal)

my original process of solving was to try and relate the two speeds with a ratio, but that method has proven unsuccessful.

I get really confused whenever dealing with angular speed so if anyone could help that'd be great!

thanks
Jim

2. Apr 6, 2010

### rock.freak667

$$\frac{\omega_B}{\omega_C} = \frac{R_C}{R_B}$$

when ωC is 100 rpm what is ωB ?

Then you know that

$$\alpha = \frac{\omega_2 - \omega_1}{t}$$