A block is suspended by a spring and the elongation produced in the spring is found to be x0. Then the block is further pulled downward by a distance x0 and released. Then acceleration of the block in its lower most position is

After release, the block will execute vertical simple harmonic motion about is equilibrium position with amplitude (2x0−x0) i.e. x0 and angular frequency ωHere ω=km and x0=mgk∴ Acceleration at the lower extreme position =ω2x0=(Km) ×mgk=g