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प्रश्न
Solve the following problem.
A 2 m long wooden plank of mass 20 kg is pivoted (supported from below) at 0.5 m from either end. A person of mass 40 kg starts walking from one of these pivots to the farther end. How far can the person walk before the plank topples?
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उत्तर
Let the person starts walking from pivot P2 as shown in the figure.
Assume the person can walk up to distance x from P1 before the plank topples. The plank will topple when the moment exerted by the person about P1 is not balanced by a moment of force due to plank about P2.
∴ For equilibrium,
40 × x = 20 × 0.5
∴ x = `1/4` = 0.25 m
Hence, the total distance walked by the person is 1.25 m.
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