Oscillations - Result Question 42
46. A block of mass $M$ is attached to the lower end of a vertical spring. The spring is hung from a ceiling and has force constant value $k$. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be:
(a) $2 Mg / k$
(b) $4 Mg / k$
(c) $Mg / 2 k$
(d) $Mg / k$
[2009]
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Answer:
Correct Answer: 46. (d)
Solution:
- (d) Restoring force, $f^{\prime}=-kx$
where $x$ is the extension produced in the spring.
Weight of the mass acting downward $=Mg$.
In equilibrium
$kx=Mg \quad$ or $x=\frac{Mg}{k}$
