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A block of mass 25 kg is raised by a 50k...

A block of mass 25 kg is raised by a 50kg man 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 `700N`, which mode should the man adopt to lift the block without the floor yielding?

Text Solution

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Mass of the block, m = 25 kg, mass of the man, M = 50 kg Force applied to lift the block F = mg `=25xx9.8` = 245 N weight of the man, M g `= 50xx9.8=490 N`
(a) When the block is raised by the men by applying force F in upward direction, reaction equal and opposite of F will act on the floor in addition to the weight of the man.
`therefore"actin on the floor"" "Mg +F = 490 +245=735N`
(b) When the block is raised by the mass applying force F over rhw eopw (passed over the pully) in downward direction, reacton equal and opposite to F will act on the floor,
`therefore"actin on the floor"" "Mg +F = 490 +245=245N`
floor yields to a normal force of 700 n, hte mode (b) should be adopted by the man to life block.
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