A vertical spring is fixed to one of its end and a massless plank pland fitted to other end, A block is released from a height (h) as shown, spring is in relaxed position then choose the correct statement.
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Options

A. The maximum compression of the spring does not depend on h.
B. The maximum kinetic energy of the block does not depend on h.
C. the compression of the spring at maximum (KE) of the block does not depend on h.
D. The maximum compression of the spring does not depend on k.

Answer

C

Explanation

After falling on plank downward force on block is mh and upward force is kx. Kinetic energy will increase when `mggtkx`. And it will decreae when `kxgtmg`. Therefore it is maximum when,
`kx-mg` or, `x=(mg)/k`
and this does not depend on h.