[填空题]
The forearm in Fig. 85 tsp8.h 8ra .iz3ukli–45wg- csx3jjj8h6-du u .c5acd im(tu)( 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