The figure shows a swing consisting of two identical vertical light springs attached symmetrically to a light horizontal cross-bar and supported from a strong fixed horizontal beam. When a mass of 24 kg is placed at the mid-point of the cross-bar, both springs extend by 30 cm to the position \(A\), as shown.
\includegraphics{figure_6}
Each spring has natural length \(l\) m and modulus of elasticity \(\lambda\) N.
- Show that \(\lambda = 392l\). [2 marks]
The 24 kg mass is left on the bar and the bar is then displaced downwards by a further 20 cm.
- Prove that the system comprising the bar and the mass now performs simple harmonic motion with the centre of oscillation at the level \(A\). [5 marks]
- Calculate the number of oscillations made per second in this motion. [3 marks]
- Find the maximum acceleration which the mass experiences during the motion. [2 marks]