| Exam Board | Edexcel |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2017 |
| Session | June |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Newton's laws and connected particles |
| Type | Vertically connected particles, air resistance |
| Difficulty | Moderate -0.3 This is a straightforward connected particles problem requiring application of Newton's second law to the system and then to one particle. The setup is simple (vertical motion only, two particles, one force), and the solution follows a standard method: find acceleration from F=ma for the whole system, then analyze forces on one particle to find the thrust. Slightly easier than average due to the direct approach and minimal algebraic manipulation required. |
| Spec | 3.03c Newton's second law: F=ma one dimension3.03k Connected particles: pulleys and equilibrium |
| Answer | Marks | Guidance |
|---|---|---|
| Working/Answer | Marks | Guidance |
| \(T - 0.5g = 0.5a\) | M1 A1 | M1 for equation of motion for \(P\) or \(Q\); A1 correct equation |
| \(15 - T - 0.75g = 0.75a\) | M1 A1 | M1 for second equation of motion; A1 correct equation |
| OR: \(15 - 0.5g - 0.75g = 1.25a\) | Combined equation | |
| \(a = 2.2\ \text{ms}^{-2}\) | M1 A1 (6) | M1 for solving two three-term equations for \(T\) |
| \(T = 6\ \text{N}\) | A1 for \(6\) N (must be positive) |
# Question 5:
| Working/Answer | Marks | Guidance |
|---|---|---|
| $T - 0.5g = 0.5a$ | M1 A1 | M1 for equation of motion for $P$ or $Q$; A1 correct equation |
| $15 - T - 0.75g = 0.75a$ | M1 A1 | M1 for second equation of motion; A1 correct equation |
| OR: $15 - 0.5g - 0.75g = 1.25a$ | | Combined equation |
| $a = 2.2\ \text{ms}^{-2}$ | M1 A1 (6) | M1 for solving two three-term equations for $T$ |
| $T = 6\ \text{N}$ | | A1 for $6$ N (must be positive) |5.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{c809d34e-83db-4a16-a831-001f9f36b1c3-14_346_241_262_845}
\captionsetup{labelformat=empty}
\caption{Figure 2}
\end{center}
\end{figure}
A vertical light rod $P Q$ has a particle of mass 0.5 kg attached to it at $P$ and a particle of mass 0.75 kg attached to it at $Q$, to form a system, as shown in Figure 2. The system is accelerated vertically upwards by a vertical force of magnitude 15 N applied to the particle at $Q$. Find the thrust in the rod.\\
\hfill \mbox{\textit{Edexcel M1 2017 Q5 [6]}}