| Exam Board | WJEC |
|---|---|
| Module | Unit 4 (Unit 4) |
| Year | 2018 |
| Session | June |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Vectors Introduction & 2D |
| Type | Newton's second law with vector forces (find acceleration or force) |
| Difficulty | Moderate -0.3 This is a straightforward mechanics question requiring direct application of Newton's second law (F=ma) to find acceleration, then standard kinematics integration. Part (a) involves simple division and magnitude calculation; part (b) requires integrating acceleration twice with given initial conditions. All steps are routine with no problem-solving insight needed, making it slightly easier than average but not trivial due to 3D vectors and multiple steps. |
| Spec | 1.10b Vectors in 3D: i,j,k notation3.02g Two-dimensional variable acceleration3.03d Newton's second law: 2D vectors |
A particle of mass 2 kg moves under the action of a constant force F N, where F is given by
$$\mathbf{F} = -3\mathbf{i} + 4\mathbf{j} - 5\mathbf{k}.$$
\begin{enumerate}[label=(\alph*)]
\item Find the magnitude of the acceleration of the particle. [3]
\item Given that at time $t = 0$ seconds, the position vector of the particle is $2\mathbf{i} - 7\mathbf{j} + 9\mathbf{k}$ and it is moving with velocity $3\mathbf{i} - 2\mathbf{j} + \mathbf{k}$, find the position vector of the particle when $t = 2$ seconds. [3]
\end{enumerate}
\hfill \mbox{\textit{WJEC Unit 4 2018 Q10 [6]}}