Mathematics 9709 · AS & A Level · Newton's laws of motion
Newton's laws of motion — practice question
At point $O$ on a straight horizontal test track, racing cars $A$ and $B$ are stationary side by side. The mass of $A$ is $1200\text{ kg}$. A’s engine exerts a constant driving force of $4500\text{ N}$. By the time $A$ reaches point $P$, its speed is $25\text{ m s}^{-1}$. The distance $OP$ is $d\text{ m}$. From $O$ to $P$, the work done against the resistance force acting on $A$ is $75\,000\text{ J}$.
(a)[3]
Hence, show that $d = 100$.
(b)[3]
Car $B$ sets off at the same instant as car $A$. The two cars reach $P$ together and with the same speed. The engine of $B$ provides a driving force of $3200\text{ N}$, and the car experiences a constant resistance to motion of $1200\text{ N}$. Find the mass of $B$.
(c)[3]
Find the steady speed that $B$ can maintain when its engine works at the same rate as it does at $P$.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A work-energy equation is attempted.” …