| Exam Board | OCR |
|---|---|
| Module | M2 (Mechanics 2) |
| Year | 2013 |
| Session | January |
| Marks | 8 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Moments |
| Type | Rod on smooth peg or cylinder |
| Difficulty | Standard +0.3 This is a standard M2 statics problem involving a rod in limiting equilibrium with three forces (reaction at P, friction and normal reaction at A, and weight). Students must resolve forces in two directions and take moments about a suitable point. While it requires careful setup and multiple equations, the techniques are routine for M2 and the problem follows a familiar template with no novel insights required. |
| Spec | 3.03m Equilibrium: sum of resolved forces = 03.03n Equilibrium in 2D: particle under forces3.03t Coefficient of friction: F <= mu*R model3.03u Static equilibrium: on rough surfaces3.04a Calculate moments: about a point3.04b Equilibrium: zero resultant moment and force |
\includegraphics{figure_5}
A uniform rod $AB$, of mass 3 kg and length 4 m, is in limiting equilibrium with $A$ on rough horizontal ground. The rod is at an angle of 60° to the horizontal and is supported by a small smooth peg $P$, such that the distance $AP$ is 2.5 m (see diagram). Find
\begin{enumerate}[label=(\roman*)]
\item the force acting on the rod at $P$, [3]
\item the coefficient of friction between the ground and the rod. [5]
\end{enumerate}
\hfill \mbox{\textit{OCR M2 2013 Q5 [8]}}