[填空题]
The forearm in Fig. 8–45 accelerates a 3.y/nd y9s .u)9i:aid ryi0bz4s6-kg ballz8 e 41z9o8jsf7mqglu 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