[填空题]
The forearm in Fig. h5 ld1b0(yh yh8–/b h*l4ped.g wxm)abu -i()vf 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