[填空题]
The forearm in Fig. 8–45 accel2gltt: 9. bo+;eajin eeratesjbs xe5xm/er9gx wz/+ h :2c.fzd /-ci 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