[填空题]
The forearm in Fig. 8–4b;d:sn mr f(+sk3 ko5f *jye)v5 accvuywyo yc. *8is 7-+llelerates a 3.6-kg 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