Determine the torques about the axis of rotation P produced

Determine the torques about the axis of rotation P produced by each of the four forces shown in Figure P7.1. All forces have magnitudes of 120 N and are exerted a distance of 2.0 m from P on some unshown object O.

Solution

Torque of F1, T1 = F1*0 = 0

Torque of F2 = T2 = F2*cos(40 deg) *2 = 120*cos(40 deg)*2 = 183.9 N.m

Similarly, T3 = -120*2 = -240 N.m

and T4 = 120*2 = 240 N.m

So, net torque , Tnet = T1 +T2 + T3 +T4

So, Tnet = 0 + 183.9 -240 +240 = 183.9 N.m clockwise <------answer