Question

A box of weight W = 500 N is set on a light plank d = 5 meters from a fulcrum. A force F is applied to the plank on the opposite side of the fulcrum a distance D = 10 meters from the fulcrum, as shown. What minimum force is required to lift the box?

Answer 1

Given data

*The weight of the box is W = 500 N

*The distance of the plank from the fulcrum is d = 5 m

*The given force at a distance from the fulcrum is D = 10 m

The minimum force is required to lift the box is given by the net torque as

`\begin{gathered} \tau=0 \\ W* d-F* D=0 \\ W* d=F* D \end{gathered}`

Substitute the known values in the above expression as

`\begin{gathered} 500*5=F*10 \\ F=250\text{ N} \end{gathered}`

Hence, the minimum force is required to lift the box is F = 250 N