A lever of length 100 cm has effort of 15 kgf at a distance of 40 cm from the fulcrum at one end. What load can be applied at its other end?

Given,

Lever length = 100 cm

Effort = 15 kgf

Effort arm = 40 cm

Load arm = Lever length = 100 cm

Mechanical advantage of a lever is :

$\text {Mechanical Advantage}=\dfrac{\text {Load}}{\text {Effort}}=\dfrac{\text {Effort Arm}}{\text {Load Arm}} \\[1 em] \Rightarrow \text {Load} = \dfrac{\text {Effort Arm}}{\text {Load Arm}}\ \times \text {Effort} = \dfrac{40 \text { cm}}{100 \text { cm}}\ \times 15 \text { kgf}\\[1 em] \Rightarrow \text {Load} = \dfrac{4}{10}\ \times 15 \text { kgf} = 6 \text { kgf}$

A load of 6 kgf should be applied for the effort of 15 kgf.