| Exam Board | WJEC |
|---|---|
| Module | Unit 2 (Unit 2) |
| Year | 2024 |
| Session | June |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Variable acceleration (1D) |
| Type | Velocity from acceleration by integration |
| Difficulty | Moderate -0.3 This is a straightforward mechanics question requiring application of F=ma, integration to find velocity, and interpretation of velocity/acceleration signs. Part (a) is direct substitution, part (b) is routine integration with a boundary condition, and part (c) requires checking if velocity and acceleration have the same sign. All techniques are standard A-level mechanics with no novel problem-solving required, making it slightly easier than average. |
| Spec | 3.03c Newton's second law: F=ma one dimension3.03d Newton's second law: 2D vectors6.06a Variable force: dv/dt or v*dv/dx methods |
A particle, of mass 4 kg, moves in a straight line under the action of a single force $F$ N, whose magnitude at time $t$ seconds is given by
$$F = 12\sqrt{t} - 32 \quad \text{for} \quad t \geqslant 0.$$
\begin{enumerate}[label=(\alph*)]
\item Find the acceleration of the particle when $t = 9$. [2]
\item Given that the particle has velocity $-1\text{ms}^{-1}$ when $t = 4$, find an expression for the velocity of the particle at $t$ s. [3]
\item Determine whether the speed of the particle is increasing or decreasing when $t = 9$. [2]
\end{enumerate}
\hfill \mbox{\textit{WJEC Unit 2 2024 Q8 [7]}}