A cylinder having a mass of 2.0kg can rotate about its central axis through point O. Forces are applied as show: F1 = 6.0N, F2 = 4.0N, F3 = 2.0 N, and F4 = 5.0N. Also, r = 5.0cm and R = 12 cm. Find the (a) magnitude and (b) direction of the angular acceleration of the cylinder.
The Attempt at a Solution
as of yet, I'm not looking for the solution to the entire problem, because I'm stuck on the first step of finding the net torque. this is what i have:
net torque = F1R - F2R - F3r + F4R = 6*0.12 - 4*0.12 - 2*0.05 + 0 = 0.14 N m
the book's solution for the net torque is 71 N m. i also got a similar problem wrong for presumably the same reason. the units are Newtons and meters, and I'm sure my calculator works fine. what is going on here?