JAMB Physics 2024 Paper

Concept:The mechanical advantage of a machine is found from its efficiency and velocity ratio.Then the effort is the load divided by the mechanical advantage.Explanation:Efficiency is given by the formula:$$\text{Efficiency} = \frac{\text{Mechanical Advantage}}{\text{Velocity Ratio}} \times 100\%$$Convert efficiency to a decimal: $60\% = 0.6$.Velocity ratio, $\text{V.R.} = 2$.Substitute into the efficiency formula:$$0.6 = \frac{\text{M.A.}}{2}$$Solve for mechanical advantage:$$\text{M.A.} = 0.6 \times 2 = 1.2$$Mechanical advantage is also defined as:$$\text{M.A.} = \frac{\text{Load}}{\text{Effort}}$$The load is $300\,\mathrm{N}$, so:$$1.2 = \frac{300}{\text{Effort}}$$Rearrange to find the effort:$$\text{Effort} = \frac{300}{1.2} = 250\,\mathrm{N}$$Answer:The effort applied is $250\,\mathrm{N}$, which matches option C.