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A monkey is descending from the branch of a tree with constant acceleration. If the breaking strength of the branch is 75% of the weight of the monkey, the minimum acceleration with which the monkey can slide down without breaking the branch is

Asked in CBSE PMT 1993 · Chains, ropes and internal forces

Answer: (3) g/4

Step-by-step solution

Given: the branch breaks above T=0.75 mg; the monkey slides down with acceleration a.

Idea: the faster the monkey accelerates downwards, the less the branch has to hold — so the minimum safe acceleration goes with the maximum allowed tension.

Newton's second law, taking down as positive: mg-T=ma.

At the limit, T=0.75 mg.

mg-0.75 mg=ma.

0.25 mg=ma, and the mass cancels.

a=g/4.

Why the other options are wrong

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