A rod is attached to a wall with a hinge. An upwards force of 10 N is applied to the rod at a point 3 m from the hinge. Another force is applied downwards 4 m from the hinge. What must the magnitude of this downwards force be to balance the torque from the upwards force? 10 Newtons 3 meters 4 meters Solution Given F1 = 10 N , at 3 m and F2 = ? , at 4 m from the hinge the moment of torque with respect to hinge F1*r1 -F2*r2 =0 10*3 - F2*4 =0 solving for F2 F2 = 7.5 N so that the system is in equilibrium if F2 is applied at 4 m from hinge with magnitude of 7.5 N downward .