1. The forearm in Fig. 10 52 accelerates a 3.6-kg ball at 7.0 m /s 2 by means of the triceps muscle,

1. The forearm in Fig. 10 52 accelerates a
3.6-kg ball at 7.0 m /s2 by means of the triceps

muscle, as shown. Calculate (a) the torque needed, and (b) the force that must
be exerted

by the triceps muscle. Ignore the mass of the arm.

FIGURE 10-52

2. A 0.72 m diameter solid sphere can be
rotated about an axis through its center by a torque of 10.8m N which
accelerates it uniformly from rest through a total of 180 revolutions in 15.0
s. What is the mass of the sphere?