What is the net torque on the pulley about the axle? (Figure 1 above)
PLEASE EXPLAIN ALL PARTS OF EQUATION AND WHAT THEY MEAN FOR BEST ANSWER.(please don't just put pi rad MR etc explain what it is)
(30N-20N)*0.02m = 0.2 N-m
The axle is in the center of the pulley. Both forces exert a torque around the axle. Torque is the force times the the perpendicular distance. It is clear from the picture the forces are tangential to the pulley and so perpendicular to the axle.
Since the forces are creating opposing torques (think of how the wheel would rotate if a force was applied by either of these forces) The one on the left would create a coutner clockwise torque, the one of the right clockwise. Since they are an equal distance from the axle, you can just subtract these forces and multiply by the distance they are from the axle, which is 0.02m (half of the diameter)