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A man weighing 80kg is standing in a trolley 320kg .the trolley is resting on frictional horizontal rails. If the man starts walking on the trolley with a speed of 1m/s then after 4sec his displacement relative to the ground will be |
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Answer» Let V = velocity of man with respect to groundV = velocity of trolley with respect to groundV = velocity of man with respect to trolley = 1 m/sLet M = mass of person = 80 kgLet M' = the mass of trolley = 320kgfrom relative motion V = V - V --------------------(1)Initially trolley and man were at rest initial momentum = 0According to law of conservation of momentumVM + VM' = 0Substituting value of V from equation (1) VM + (V - V)M' = 0 ⇒ V(M + M') - VM'V(320 + 80) = 1(320) ⇒ V = 320/400 = 0.8 m/sThus displacement of man with respect to observer = V × time = 0.8 × 4 = 3.2 m |
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