A person of mass 60 kg wants to lose 5 kg by going up and down a 10 m high stairs

thermodynamics
cbse

#1

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


#2

Here, m = 60kg, g =10m/s , h = 10m
In going up and down once, number of kilocalories burnt
= (mgh + mgh/2)= 3/2 mgh
= 3/2 x 60x10x10/4.2x1000=6/2.8 kcal
Total number of kilocalories to be burnt for losing 5 kg of weight = 5x7000 = 35000kcal

Number of times of the person has to go up and down the stairs = 35000/6/2.8 times