A wrench with a length of 15 cm is being used to unscrew a 3 cm bolt. If a torque of 1 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?

1 Answer
Apr 30, 2018

Let's derive the force needed to unscrew the bolt,

tau_"bolt" = rF

=> tau_"bolt"/r = F approx 33.3"N"

Now, recall,

tau = rFsintheta

Let's assume theta = 90° in this case. Hence,

=> tau_"min" = rF approx 5"N"*"m"

is the minimum torque needed to unscrew the bolt with the torque wrench.