A particle of mass \(0.5\) kg is projected vertically upwards from ground level with a speed of \(20 \text{ ms}^{-1}\). It comes to instantaneous rest at a height of \(10\) m above the ground. As the particle moves it is subject to air resistance of constant magnitude \(R\) newtons. Using the work-energy principle, or otherwise, find the value of \(R\). [6]

$\frac{1}{2} \times 0.5 \times 20^2 \; ; \quad 0.5g \times 10$ | B1 B1 |
$10R = \frac{1}{2} \times 0.5 \times 20^2 - 0.5g \times 10$ | M1 A1 |
$\Rightarrow R = 5.1$ | DM1 A1 |

**Total: [6]**

---

A particle of mass $0.5$ kg is projected vertically upwards from ground level with a speed of $20 \text{ ms}^{-1}$. It comes to instantaneous rest at a height of $10$ m above the ground. As the particle moves it is subject to air resistance of constant magnitude $R$ newtons. Using the work-energy principle, or otherwise, find the value of $R$.
[6]

\hfill \mbox{\textit{Edexcel M2 2010 Q3 [6]}}