| Exam Board | Edexcel |
|---|---|
| Module | Paper 3 (Paper 3) |
| Year | 2023 |
| Session | June |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Newton's laws and connected particles |
| Type | Block on rough horizontal surface – accelerating (finding acceleration or applied force) |
| Difficulty | Moderate -0.8 This is a straightforward application of Newton's second law and friction concepts with clear horizontal forces. Part (a) is trivial (R = mg), part (b) uses F = ma directly, and part (c) applies F = μR. All steps are standard textbook exercises requiring only routine recall and substitution, making it easier than average. |
| Spec | 3.03b Newton's first law: equilibrium3.03f Weight: W=mg3.03l Newton's third law: extend to situations requiring force resolution3.03r Friction: concept and vector form3.03t Coefficient of friction: F <= mu*R model |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Mark | Guidance |
| \(R = 5g = 49\) (N) | B1 | Allow either \(5g\) or \(49\). No penalty for using \(g = 9.81\) or \(10\). Ignore any working. Must be positive. B0 if \(m\) is involved. Could be seen on diagram. |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Mark | Guidance |
| \(28 - F = 5 \times 1.4\) | M1 | Equation with correct terms, dimensionally correct, condone sign errors. |
| \(F = 21\) | A1 | cao but allow \(\frac{15g}{7}\). Ignore units. |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Mark | Guidance |
| \(\mu = 0.43\) (2sf required) | B1ft | \(\mu = \frac{\text{their (b)}}{\text{their (a)}}\). Answer must be a positive number given to 2sf. B0 if \(g = 9.81\) or \(10\) used. Do not allow restarts. Allow \(\mu > 1\). |
## Question 2:
**Part (a)**
| Answer | Mark | Guidance |
|--------|------|----------|
| $R = 5g = 49$ (N) | B1 | Allow either $5g$ or $49$. No penalty for using $g = 9.81$ or $10$. Ignore any working. Must be positive. B0 if $m$ is involved. Could be seen on diagram. |
**Part (b)**
| Answer | Mark | Guidance |
|--------|------|----------|
| $28 - F = 5 \times 1.4$ | M1 | Equation with correct terms, dimensionally correct, condone sign errors. |
| $F = 21$ | A1 | cao but allow $\frac{15g}{7}$. Ignore units. |
**Part (c)**
| Answer | Mark | Guidance |
|--------|------|----------|
| $\mu = 0.43$ (2sf required) | B1ft | $\mu = \frac{\text{their (b)}}{\text{their (a)}}$. Answer must be a positive number given to 2sf. B0 if $g = 9.81$ or $10$ used. Do not allow restarts. Allow $\mu > 1$. |
---2.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{f9dc8158-8ed8-4138-9c75-050cf52e6f7e-04_83_659_267_703}
\captionsetup{labelformat=empty}
\caption{Figure 1}
\end{center}
\end{figure}
A particle $P$ has mass 5 kg .\\
The particle is pulled along a rough horizontal plane by a horizontal force of magnitude 28 N .
The only resistance to motion is a frictional force of magnitude $F$ newtons, as shown in Figure 1.
\begin{enumerate}[label=(\alph*)]
\item Find the magnitude of the normal reaction of the plane on $P$
The particle is accelerating along the plane at $1.4 \mathrm {~m} \mathrm {~s} ^ { - 2 }$
\item Find the value of $F$
The coefficient of friction between $P$ and the plane is $\mu$
\item Find the value of $\mu$, giving your answer to 2 significant figures.
\end{enumerate}
\hfill \mbox{\textit{Edexcel Paper 3 2023 Q2 [4]}}