[问答题]
Two blocks, each of maa9*u:t/v *v vstvqj7k ss m, arc+dzko0n;2n1 z k,r kg5p a:bg8s uk-fe attached to the ends of a massless rod which pivots as shown in Fig. 8–40. Initially the rod is held in the horizontald8,k fu-rk;:bc5o knpzk+ n2gzgsa 10 position and then released. Calculate the magnitude and direction of the net torque on this system.