A body of mass M is released from a height h to a scale pan hung from a spring as shown in fig (9). The spring constant of the spring is k, the mass of the scale pan is negligible and the body does not bounce relative to the pan, then the amplitude of vibration is

Let y be the displacement of the pan when the mass m hits it. Decrease in potential energy of mass =mg(h+y),y= amplitude. Increase in elastic potential energy of spring=12ky2 ∴ mg(h+y)=12ky2 or y2−2mgry−2mghk=0 y2−2mgry−2mghk=0 y=(2mg/k)±(2mg/k)2+4(2mgh/k)2 Reiecting negative sign, the total extension is y=mgk+mgk1+2hkmg =mgk1+1+2hkmg