| Exam Board | Edexcel |
|---|---|
| Module | M2 (Mechanics 2) |
| Year | 2010 |
| Session | June |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Work done and energy |
| Type | Acceleration from power and speed |
| Difficulty | Moderate -0.3 This is a standard M2 power-force-velocity question with straightforward application of P=Fv and F=ma on an incline. Part (a) uses equilibrium at constant speed, part (b) applies Newton's second law with the new power. Both parts follow routine procedures with no novel insight required, making it slightly easier than average. |
| Spec | 6.02k Power: rate of doing work6.02l Power and velocity: P = Fv |
A car of mass 750 kg is moving up a straight road inclined at an angle $\theta$ to the horizontal, where $\sin \theta = \frac{1}{15}$. The resistance to motion of the car from non-gravitational forces has constant magnitude $R$ newtons. The power developed by the car's engine is 15 kW and the car is moving at a constant speed of 20 m s$^{-1}$.
\begin{enumerate}[label=(\alph*)]
\item Show that $R = 260$.
(4)
\end{enumerate}
The power developed by the car's engine is now increased to 18 kW. The magnitude of the resistance to motion from non-gravitational forces remains at 260 N. At the instant when the car is moving up the road at 20 m s$^{-1}$ the car's acceleration is $a$ m s$^{-2}$.
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{1}
\item Find the value of $a$.
(4)
\end{enumerate}
\hfill \mbox{\textit{Edexcel M2 2010 Q4}}