M5 June 2011 Q1
1. A particle moves from the point \(A\) with position vector \((3\mathbf{i} - \mathbf{j} + 3\mathbf{k})\) m to the point \(B\) with position vector \((\mathbf{i} - 2\mathbf{j} - 4\mathbf{k})\) m under the action of the force \((2\mathbf{i} - 3\mathbf{j} - \mathbf{k})\) N. Find the work done by the force. (4)
| Scheme | Marks |
|---|---|
| \(\mathbf{AB} = (\mathbf{i} - 2\mathbf{j} - 4\mathbf{k}) - (3\mathbf{i} - \mathbf{j} + 3\mathbf{k}) = (-2\mathbf{i} - \mathbf{j} - 7\mathbf{k})\) | M1 A1 |
| \((2\mathbf{i} - 3\mathbf{j} - \mathbf{k}).(-2\mathbf{i} - \mathbf{j} - 7\mathbf{k}) = -4 + 3 + 7 = 6\) J | M1 A1 |
| (4 marks) |