| Exam Board | OCR MEI |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2013 |
| Session | January |
| Marks | 8 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Newton's laws and connected particles |
| Type | Single particle, Newton's second law – scalar (1D, horizontal or inclined) |
| Difficulty | Moderate -0.8 This is a straightforward mechanics question requiring basic kinematic equations (part i), resolving forces and applying F=ma (part ii), and conceptual understanding of resultant forces (part iii). All techniques are standard M1 content with no novel problem-solving required, making it easier than average. |
| Spec | 3.02d Constant acceleration: SUVAT formulae3.03d Newton's second law: 2D vectors3.03e Resolve forces: two dimensions |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| \(s = ut + \frac{1}{2}at^2\) | M1 | Substitution required |
| \(7.2 = \frac{1}{2}\times a\times 6^2\) | A1 | |
| \(a = 0.4\text{ ms}^{-2}\) | A1 | Cao |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| \(F = ma\) | M1 | Attempt at Newton's second law |
| M1 | Attempt at resolving both \(S\) and \(T\) | |
| \(300\cos30° + 175\cos15° - R = 1000\times0.4\) | A1 | Correct elements present and no extras; follow through for \(a\) |
| \(R = 28.8\text{ N}\) | A1 | Cao |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| The resistance perpendicular to the line of motion has been ignored. | B1 | Allow: There is also a sideways resistance force |
## Question 3:
**Part (i)**
| Answer | Marks | Guidance |
|--------|-------|----------|
| $s = ut + \frac{1}{2}at^2$ | M1 | Substitution required |
| $7.2 = \frac{1}{2}\times a\times 6^2$ | A1 | |
| $a = 0.4\text{ ms}^{-2}$ | A1 | Cao |
**Part (ii)**
| Answer | Marks | Guidance |
|--------|-------|----------|
| $F = ma$ | M1 | Attempt at Newton's second law |
| | M1 | Attempt at resolving both $S$ and $T$ |
| $300\cos30° + 175\cos15° - R = 1000\times0.4$ | A1 | Correct elements present and no extras; follow through for $a$ |
| $R = 28.8\text{ N}$ | A1 | Cao |
**Part (iii)**
| Answer | Marks | Guidance |
|--------|-------|----------|
| The resistance perpendicular to the line of motion has been ignored. | B1 | Allow: There is also a sideways resistance force |
---3 Fig. 3 shows two people, Sam and Tom, pushing a car of mass 1000 kg along a straight line $l$ on level ground.
Sam pushes with a constant horizontal force of 300 N at an angle of $30 ^ { \circ }$ to the line $l$.\\
Tom pushes with a constant horizontal force of 175 N at an angle of $15 ^ { \circ }$ to the line $l$.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{13f555cc-d506-48e5-a0e4-225cae4251dc-4_291_1132_534_479}
\captionsetup{labelformat=empty}
\caption{Fig. 3}
\end{center}
\end{figure}
(i) The car starts at rest and moves with constant acceleration. After 6 seconds it has travelled 7.2 m .
Find its acceleration.\\
(ii) Find the resistance force acting on the car along the line $l$.\\
(iii) The resultant of the forces exerted by Sam and Tom is not in the direction of the car's acceleration. Explain briefly why.
\hfill \mbox{\textit{OCR MEI M1 2013 Q3 [8]}}