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A person of mass 60 kg wants to lose 5 k...

A person of mass 60 kg wants to lose 5 kg by going up and down a 10 m high stairs. Assume he burns twice as much fat while going up than coming down. If 1 kg of fat is burnt on expending 7000 kilo calories, how many times must he go up and down to reduce his weight by 5 kg ?

Text Solution

Verified by Experts

Height of the stairs h = 10 m
Work done to burn 1 kg of fat = 7000 k cal
`therefore` Work done to burn 5 kg of fat
=5 x 7000 = 35000 k cal
Work done towards burning of fat in up and down the stairs,
`=mgh+1/2mgh`
`=3/2mgh`
`=3/2xx60xx10xx10`
=9000 J
`=9000xx1/4.2` cal
=2142.85 cal
`therefore` For energy of 2142.85 cal one trip (up and down) of stairs needed
Hence , for energy of `35xx10^6` cal n trip (up and down) of stairs needed.
`therefore n=(35xx10^6)/(2142.85)=0.01633xx10^6`
=16330 times
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