[问答题]
Two blocks, each of mass m, are attached to the ends) sbn6uibd5az6wwt1 h(g9s+ v of a massless rod which ;-gb/fa8u *y xulnoy (hi7ry/ pivots as shown in Fig. 8–40. Initiall/8-o7yayi (frg xuun/;*ybh ly the rod is held in the horizontal position and then released. Calculate the magnitude and direction of the net torque on this system.