A vertical spring with force constant $k$ is fixed on a table. A ball of mass $m$ at a height $h$ above the…

A vertical spring with force constant $k$ is fixed on a table. A ball of mass $m$ at a height $h$ above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance $d$. The net work done in the process is
  1. $m g(h+d)-\frac{1}{2} k d^2$
  2. $m g(h-d)-\frac{1}{2} k d^2$
  3. $m g(h-d)+\frac{1}{2} k d^2$
  4. $m g(h+d)+\frac{1}{2} k d^2$

Solution

Net work done = work done by gravitational force + work done by spring force $=m g(h+d)-\frac{1}{2} k d^2$

Asked in: NEET 2007

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