Moderate -0.3 This is a straightforward work-energy problem requiring application of the work-energy principle with two components: kinetic energy change and work against resistance. The calculation involves standard formulas (KE = ½mv², work = force × distance) with clear given values and a single unknown, making it slightly easier than average but still requiring proper setup of the energy equation.
1 A man has mass 80 kg . He runs along a horizontal road against a constant resistance force of magnitude \(P \mathrm {~N}\). The total work done by the man in increasing his speed from \(4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) to \(5.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) while running a distance of 60 metres is 1200 J . Find the value of \(P\).
1 A man has mass 80 kg . He runs along a horizontal road against a constant resistance force of magnitude $P \mathrm {~N}$. The total work done by the man in increasing his speed from $4 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ to $5.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ while running a distance of 60 metres is 1200 J . Find the value of $P$.\\
\hfill \mbox{\textit{CAIE M1 2018 Q1 [4]}}