Question

A light rod is being used as a lever as shown. The fulcrum is 1.20 m from the load and 2.40 m from the applied force. If the load has a mass of 18.0 kg, what force must be applied to lift the load?

Answer 1

ANSWER:

88.2

STEP-BY-STEP EXPLANATION:

In this case the torque about the fulcrum must be equal. Torque is force perpendicular distance. Therefore, the torque on both side must be equal, just like that:

$\begin{gathered} F_g\cdot d_1=F_A\cdot d_2 \\ F_g=m\cdot g \\ d_1=1.2\text{ m} \\ d_2=2.4\text{ m} \\ m=18\text{ kg} \end{gathered}$

Therefore, we replace and calculate the applied force, like this:

$\begin{gathered} 18\cdot9.8\cdot1.2=F_A\cdot2.4 \\ F_A=\frac{211.68}{2.4} \\ F_A=88.2\text{ N} \end{gathered}$

The applied force is 88.2 N