See Joyfrancis, in the 1st case the man manages to keep the block at rest and then the weight shown by the machine is 15 kg. But in the 2nd case, as the weight shown by the w-machine is 60 kg so the force applied by the man has to be different from (and more than) that applied in the 1st case. So, the block is no longer at rest but is accelerating upward in the 2nd case. Hence the acceleration term is included by INDIAN ARMY in his solution. And he is correct.
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Moderation Team
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