A wrench with a length of 20cm is used to unscrew a 52cm bolt. If a torque of 12Nm 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
Aug 13, 2017

F=60N

Explanation:

I assume the question is meant to ask what is the minimum force required to unscrew the bolt.

Torque is given by the equation:

τ=rFsinϕ

where F is the applied force, r is the distance from the pivot (axis of rotation) that the force is applied, and ϕ is the angle at which the force is applied.

We can rearrange the equation for torque to find F.

F=τrsinϕ

We are provided the following information:

  • r=20cm=0.20m

  • τ=12Nm

And it is implied that ϕ=90o since no angle—nor the necessary information to calculate one—is provided.

Note that I am not including the radius of the bolt in the measurement of the total radius because it should not affect the distance from the applied force to the bolt itself.

Therefore, we have:

F=12Nm0.20m

=60N