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Determine the value of $P$.
Mathematics 9709 · AS & A Level · Forces and equilibrium
Forces and equilibrium — practice question
A man of mass $80\,\text{kg}$ runs along a horizontal road while a constant resistance force of magnitude $P\,\text{N}$ acts opposite his motion. The total work done by the man as he increases his speed from $4\,\text{m s}^{-1}$ to $5.5\,\text{m s}^{-1}$ over a distance of $60\,\text{m}$ is $1200\,\text{J}$.
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This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct increase in kinetic energy $\frac12 \times 80 (5.5^2-4^2)=570$ (either the initial or the final KE is correct)” …
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