M3 January 2012 Q1
1. A particle of mass 0.8 kg is attached to one end of a light elastic string of natural length 0.6 m. The other end of the string is attached to a fixed point \(A\). The particle is released from rest at \(A\) and comes to instantaneous rest 1.1 m below \(A\).
Find the modulus of elasticity of the string. (4)
| Scheme | Marks |
|---|---|
| EPE \(= \dfrac{\lambda \times 0.5^2}{1.2}\) | B1 |
| GPE lost = EPE gained | M1 (used) |
| \(0.8 \times 9.8 \times 1.1 = \dfrac{\lambda \times 0.5^2}{1.2}\) | A1ft |
| \(\lambda = 41.4\) N or 41 N | A1 |
| (4 marks) |