| Exam Board | CAIE |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2021 |
| Session | November |
| Marks | 3 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Constant acceleration (SUVAT) |
| Type | Multi-phase journey: find unknown speed or time |
| Difficulty | Moderate -0.3 This is a standard SUVAT multi-stage motion problem requiring a velocity-time graph approach or systematic application of kinematic equations. While it involves three stages and solving simultaneous equations with algebraic unknowns, the structure is formulaic and commonly practiced. The problem-solving strategy is straightforward: recognize that acceleration and deceleration phases form triangles with the constant speed phase, use area under v-t graph equals total distance, and solve. Slightly easier than average due to its routine nature and clear structure. |
| Spec | 3.02c Interpret kinematic graphs: gradient and area3.02d Constant acceleration: SUVAT formulae |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Mark | Guidance |
| \(6V + 30V + 3V = 585\) or \(0.5(30+48)V = 585\) | M1 | Use of constant acceleration equations or a \(v\)-\(t\) graph. Complete method to set up an equation in \(V\) using constant acceleration equations or correct area formula in \(v\)-\(t\) graph. |
| Speed of the bus \(= 15 \text{ ms}^{-1}\) | A1 | Must be positive. |
| Total: 2 |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Mark | Guidance |
| Magnitude of deceleration \(= 2.5\) | B1 FT | OE. Do not allow \(a = -2.5\). |
| Total: 1 |
## Question 1:
**Part (a):**
| Answer | Mark | Guidance |
|--------|------|----------|
| $6V + 30V + 3V = 585$ or $0.5(30+48)V = 585$ | M1 | Use of constant acceleration equations or a $v$-$t$ graph. Complete method to set up an equation in $V$ using constant acceleration equations or correct area formula in $v$-$t$ graph. |
| Speed of the bus $= 15 \text{ ms}^{-1}$ | A1 | Must be positive. |
| | **Total: 2** | |
**Part (b):**
| Answer | Mark | Guidance |
|--------|------|----------|
| Magnitude of deceleration $= 2.5$ | B1 FT | OE. Do not allow $a = -2.5$. |
| | **Total: 1** | |1 A bus moves from rest with constant acceleration for 12 s . It then moves with constant speed for 30 s before decelerating uniformly to rest in a further 6 s . The total distance travelled is 585 m .
\begin{enumerate}[label=(\alph*)]
\item Find the constant speed of the bus.
\item Find the magnitude of the deceleration.
\end{enumerate}
\hfill \mbox{\textit{CAIE M1 2021 Q1 [3]}}