Question:
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 kilocalories, how many times must he go up and down to reduce his weight by 5 kg?
Solution:
Given,
Height of the stairs, h = 10 m
Work done to burn 5 kg of fat = (5)(7000 × 103)(4.2) = 147 × 106 J
Work done towards burning of fat in one trip = mgh + 1/2 mgh = 3/2 mgh = (3/2)(60)(10)(10) = 9 × 103 J
Therefore, no.of trips required = 16.3 × 103 times.
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