[填空题]
The forearm in Fig. 8–45 accelerates a 3.6- zwk:s):/rin x:3,lf fwxt); sh*j)s zv ar3ztkg ball at 7 $m/s^2$ by means of the triceps muscle, as shown. Calculate (a) the torque needed, $m \cdot N$ (b) the force that must be exerted by the triceps muscle. Ignore the mass of the arm. N