[填空题]
Suppose David puts a 0.ee b( m7uck.4z-z+ nmd50-kg rock into a sling of lengtyt 8ca0y+ g.4rpfzvtpn.d + 9oh 1.5 m and begins whirling the rock in a nearly horizontal circle above his head, accelerating it from rest to a rate of 120 rpm after 5.0 s. What is the torque required to achieve thina+94dv o pcrt+p8. 0y f.gztys feat, and where does the torque come from? $m \cdot N$
