| Exam Board | OCR MEI |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2011 |
| Session | January |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Newton's laws and connected particles |
| Type | Two connected particles, horizontal surface |
| Difficulty | Moderate -0.3 This is a straightforward connected particles problem requiring standard application of Newton's second law and kinematics equations. Part (i) uses v²=u²+2as to find deceleration, then F=ma for the system. Part (ii) applies F=ma to one box individually to find the rod force. The rigid rod (tow-bar) setup is simpler than string problems since it can push or pull, but the solution follows a standard textbook method with no novel insight required. |
| Spec | 3.03k Connected particles: pulleys and equilibrium3.03o Advanced connected particles: and pulleys |
5 Fig. 5 shows two boxes, A of mass 12 kg and B of mass 6 kg , sliding in a straight line on a rough horizontal plane. The boxes are connected by a light rigid rod which is parallel to the line of motion. The only forces acting on the boxes in the line of motion are those due to the rod and a constant force of $F \mathrm {~N}$ on each box.
\begin{figure}[h]
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\caption{Fig. 5}
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The boxes have an initial speed of $1.5 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ and come to rest after sliding a distance of 0.375 m .\\
(i) Calculate the deceleration of the boxes and the value of $F$.\\
(ii) Calculate the magnitude of the force in the rod and state, with a reason, whether it is a tension or a thrust (compression).
\hfill \mbox{\textit{OCR MEI M1 2011 Q5 [7]}}