Laws Of Motion Question 256

Question: With what minimum acceleration can a fireman slides down a rope while breaking strength of the rope is $ \frac{2}{3} $ of his weight[CPMT 1979]

Options:

A) $ \frac{2}{3}g $

B) g

C) $ \frac{1}{3}g $

D) Zero

Show Answer

Answer:

Correct Answer: C

Solution:

If man slides down with some acceleration then its apparent weight decreases. For critical condition rope can bear only 2/3 of his weight. If a is the minimum acceleration then, Tension in the rope $ =m(g-a) $ = Breaking strength therefore $ m(g-a)=\frac{2}{3}mg $ therefore$ a=g-\frac{2g}{3}=\frac{g}{3} $



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