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Question
A long stick rests on the surface. A person standing 10 m away from the stick. With what minimum speed an object of mass 0.5 kg should he has thrown so that it hits the stick. (Assume the coefficient of kinetic friction is 0.7).
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Solution
Given,
Distance (s) = 10 m
Mass of the object (m) = 0.5 kg
Coefficient of kinetic friction (µ) = 0.7
Work done in moving a body in horizontal surface ω
= µR × s = µmg × s
This work done is equal to initial kinetic energy of the object
`1/2mv^2` = µ mg s
∣`v^2`∣ = 2 µgs = 2 × 0.7 × 9.8 × 10
v2 = 14 × 9.8 = 137. 2
v = 11. 71 ms-1
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