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A block of mass 25 kg is raised by a 50 kg mass in two different ways as shown in Fig. What is the action on the floor by the man in the two cases? If the floor yields to a normal force of 700 N, which mode should the man adopt to lift the block without the floor yielding. |
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Answer» In the mode (a), Figure. shown the man applies an upward force of 25 kg wt. (same as weight of the block). According to Newton's third law of motion, there will be a downward reaction on the floor. The action on the floor by man = 50 kg wt + 25 kg wt = 75 kg wt = 75 x 10 N = 750 N In mode (b), the man applies an upward force of 25 kg wt. (same as the weight of the block). According to Newton's third law of motion, the reaction is in the upward direction. In this case, action on the floor by the man = 50 kg wt - 25 kg wt = 25 kg wt = (25 x 10) N = 250 N Mode (b) should be adopted |
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