Question

If a 20 inch pully runs at 350rpms, what size does the second pully have to be to run at 3500rpms?

I Don't remember the equation all I am looking for is the equation please

Answer 1

think about it. A smaller pulley has to turn faster to convey the same amount of rope. Two pulleys of radii r1 and r2 move the same amount of rope if their speeds s1 and s2 are such that

r1 * s1 = r2 * s2

Now just plug in your numbers