An ejector mechanism consists of a helical compression spring

An ejector mechanism consists of a helical compression spring having a spring constant of K = 981 × 10³ N/m. It is pre-compressed by 100 mm from its free state. If it is used to eject a mass of 100 kg held on it, the mass will move up through a distance of

From the conservation of energy after precompression,
Initial energy = Final energy

or		1	k(0.1)² =	1	+ kx² + mg(x + 0.1)
		2		2

or k(0.1)²= kx² + 2mg(x + 0.1)
or 981 × 10³ × 10^{- 2} = 981 × 10³ × x² + 2 × 100 × 9.81(x + 0.1)
or 100x² + 2x – 0.8 = 0

∴ x =	-2 ± √(2)² - 4 × 100 × 0.8
	200

Taking + ve sign, x = 100 mm