[填空题]
The forearm in Fig. 8–45sqi3* s ciyatoinf)s1mr 9.-5 accf4n g a(eu,12lt:r9h4h obi unelerates 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