# A wrench with a length of #42 cm# is being used to unscrew a #7/2 cm# bolt. If a torque of #18 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

#### 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:

#color(blue)(tau=rFsinphi)# where

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

We can rearrange the equation for torque to find

#color(red)(F=tau/(rsinphi))#

We are provided the following information:

#"r"=42"cm"=0.42"m"#

#tau=18"Nm"#

And it is implied that

**Note that I am not including the radius of the bolt in the measurement of the total radius because I am assuming that this is the radius of the body of the screw and not the head of the screw.**

Therefore, we have:

#F=(18"Nm")/(0.42"m")#

#=42.86"N"#

#~~43"N"#