Work Energy And Power Ques 48
48. 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
[2007]
(a) $m g(h+d)-\frac{1}{2} k d^{2}$
(b) $m g(h-d)-\frac{1}{2} k d^{2}$
(c) $mg(h-d)+\frac{1}{2} kd^{2}$
(d) $mg(h+d)+\frac{1}{2} kd^{2}$
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Answer:
Correct Answer: 48.(a)
Solution:
- (a)
$W=$ Potential energy stored in the spring + Loss of potential energy of mass
$W=m g(h+d)-\frac{1}{2} k d^{2}$
Gravitational potential energy of ball gets converted into elastic potential energy of the spring.
$m g(h+d)=\frac{1}{2} k d^{2}$
Net work done $=mg(h+d)-\frac{1}{2} k d^{2}=0$
BETA
