[填空题]
The forearm in Fig. 8–af+bw:pd /jl)w2 ;*qe;)o abbmc qy0k4/62lg 9xvleb p.k*rim5 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