(i)[2]
Find $R$.
(ii)[5]
The car’s engine power is raised to $12\,500\text{ W}$. The resistance forces stay the same. Find the acceleration of the car and trailer and the tension in the rod at the moment when the car’s speed is $25\text{ m s}^{-1}$.
Mathematics 9709 · AS & A Level · Energy, work and power
Energy, work and power — practice question
A $1500\text{ kg}$ car is towing a $300\text{ kg}$ trailer on a straight level road at a steady speed of $20\text{ m s}^{-1}$. The car and trailer are represented as two particles joined by a light rigid horizontal rod. The car’s engine has a power output of $6000\text{ W}$. The resistances to motion are constant, with $R\text{ N}$ acting on the car and $80\text{ N}$ acting on the trailer.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Using $F = \dfrac{P}{v}$, the driving force is $F = \dfrac{6000}{20} = 300\text{ N}$” …
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