| Exam Board | OCR |
|---|---|
| Module | M1 (Mechanics 1) |
| Marks | 11 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Friction |
| Type | Two-part friction scenarios |
| Difficulty | Moderate -0.3 This is a standard M1 mechanics problem involving resolving forces, friction, and Newton's second law. Parts (i)-(iii) are routine applications of equilibrium and F=μR with straightforward resolution of forces. Part (iv) requires applying F=ma after calculating the new friction force, but follows a standard template. The calculations are direct with no conceptual challenges beyond basic M1 content. |
| Spec | 3.03e Resolve forces: two dimensions3.03r Friction: concept and vector form3.03t Coefficient of friction: F <= mu*R model3.03u Static equilibrium: on rough surfaces3.03v Motion on rough surface: including inclined planes |
\includegraphics{figure_4}
A block of mass $2$ kg is at rest on a rough horizontal plane, acted on by a force of magnitude $12$ N at an angle of $15°$ upwards from the horizontal (see diagram).
\begin{enumerate}[label=(\roman*)]
\item Find the frictional component of the contact force exerted on the block by the plane. [2]
\item Show that the normal component of the contact force exerted on the block by the plane has magnitude $16.5$ N, correct to 3 significant figures. [2]
\end{enumerate}
It is given that the block is on the point of sliding.
\begin{enumerate}[label=(\roman*)]
\setcounter{enumi}{2}
\item Find the coefficient of friction between the block and the plane. [2]
\end{enumerate}
The force of magnitude $12$ N is now replaced by a horizontal force of magnitude $20$ N. The block starts to move.
\begin{enumerate}[label=(\roman*)]
\setcounter{enumi}{3}
\item Find the acceleration of the block. [5]
\end{enumerate}
\hfill \mbox{\textit{OCR M1 Q4 [11]}}