Solve:-

A man weighing 70kg climbs a three-storey building. Each storey has 20 steps of height 15cm each. How many Calories of enegry does he burn?

Here,

m  = 70 kg

height of stairs  = 15 cm

no. of stairs  = 20

Height of one storey = 20×15 cm

   = 300 cm

No. of storey  = 3

Total height    = 3×300 = 900 cm = 9 m

Force on man  = mg = 70×9.8 N

   =  686 N

Now work done = Force × displacement

  = 686 × 9 Joule

   = 6174 Joule

Now 1 calorie = 4.2 Joule

Thus 6174 Joule = 6174/4.2 calorie

  = 1470 cal

He burns = 1470 cal or 1.47 kcal