M2 June 2009 Q1
1. A particle of mass 0.25 kg is moving with velocity \((3\mathbf{i} + 7\mathbf{j})\) m s\(^{-1}\) when it receives the impulse \((5\mathbf{i} - 3\mathbf{j})\) N s.
Find the speed of the particle immediately after the impulse. (5)
| Scheme | Marks |
|---|---|
| \(\mathbf{I} = m\mathbf{v} - m\mathbf{u}\) | |
| \(5\mathbf{i} - 3\mathbf{j} = \dfrac{1}{4}\mathbf{v} - \dfrac{1}{4}(3\mathbf{i} + 7\mathbf{j})\) | M1A1 |
| \(\mathbf{v} = 23\mathbf{i} - 5\mathbf{j}\) | A1 |
| \(|\mathbf{v}| = \sqrt{23^2 + 5^2} = 23.5\) | M1A1 |
| (5 marks) |