[填空题]
The forearm in Fig. 8–40/2avh/cdlwg1y ub d 65 accelerates a 3.6-kg.i v orc7ez k9.oc3y-o 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