MHT CET · Physics · Laws of Motion

The minimum acceleration with which a fireman can slide down a rope of breaking strength two-third of his weight is

A zero
B \(\frac{g}{3}\)
C \(3 \mathrm{~g}\)
D \(g\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{g}{3}\)

Step-by-step Solution

Detailed explanation

If fireman slides down with some acceleration then its apparent weight decreases. For critical condition rope can bear only \(\frac{2}{3}\) of the fireman's weight. Let \(a\) is the minimum acceleration then,
Tension in the rope \(=m(g-a)=\) Breaking strength
\(\begin{array}{ll}\Rightarrow & m(g-a)=\frac{2}{3} m g \\\Rightarrow &=g-\frac{2 g}{3}=\frac{g}{3}\end{array}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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