| Exam Board | AQA |
|---|---|
| Module | M2 (Mechanics 2) |
| Year | 2012 |
| Session | January |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Topic | Power and driving force |
| Type | Find acceleration given power |
| Difficulty | Moderate -0.3 This is a straightforward M2 mechanics question requiring standard application of P=Fv and F=ma. Part (a) is a 'show that' using maximum speed (where driving force equals resistance), and part (b) applies Newton's second law with given power. Both parts follow textbook procedures with no problem-solving insight required, making it slightly easier than average. |
| Spec | 6.02l Power and velocity: P = Fv |
4 A car travels along a straight horizontal road. When its speed is $v \mathrm {~m} \mathrm {~s} ^ { - 1 }$, the car experiences a resistance force of magnitude $25 v$ newtons.
\begin{enumerate}[label=(\alph*)]
\item The car has a maximum constant speed of $42 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ on this road.
Show that the power being used to propel the car at this speed is 44100 watts.
\item The car has mass 1500 kg .
Find the acceleration of the car when it is travelling at $15 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ on this road under a power of 44100 watts.
\end{enumerate}
\hfill \mbox{\textit{AQA M2 2012 Q4 [6]}}