A rod of length L leans against a smooth vertical wall while its other end is on a smooth floor. end

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4-1.Newton's Laws of Motion

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A rod of length $L$ leans against a smooth vertical wall while its other end is on a smooth floor. The end that leans against the wall moves uniformly vertically downward. Select the correct alternative

A

The speed of lower end increases at a constant rate

B

The speed of the lower end decreases but never becomes zero

C

The speed of the lower end gets smaller and smaller and vanishes when the upper end touches the ground

D

The speed of the lower end remain constant till upper end touches the ground

Solution

(c)

Using constraint motion relation

$v^{\prime} \cos \theta=v \sin \theta$

$v^{\prime}=v \tan \theta$

As $\theta$ keeps on decreasing, $\tan \theta$ will also decrease and at last $\theta$ will become zero and $v^{\prime}=0$

Standard 11

Physics

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