# A wrench with a length of 24 cm is used to unscrew a 5/2 cm bolt. If a torque of 5 Nm is needed to overcome the friction keeping the bolt in place, what is the minimum torque that must be applied to the wrench to unscrew the bolt?

vec \tau=vec r\timesvec F; \qquad \tau = r.F.sin90^0=r.F
r=0.24m; \qquad \tau = 5 N.m; \qquad F=\tau/r = 21 $N$