[填空题]
The forearm in Fig. ifg4l;q2 ss34 t,uafdqiu- - kogyav. sv g;.xgurpn9;,y9 t98–45 accelerates 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