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

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Answer 1 · 2018-04-30T21:07:23

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

$τ_{bolt} = r F$ $tau_"bolt" = rF$

$\Rightarrow \frac{τ_{bolt}}{r} = F \approx 33.3 N$ $=> tau_"bolt"/r = F approx 33.3"N"$

Now, recall,

$τ = r F sin θ$ $tau = rFsintheta$

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.

A wrench with a length of 15 cm15cm15 cm is being used to unscrew a 3 cm3cm3 cm bolt. If a torque of 1 Nm1Nm1 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?