Question

answer the question.!!!! ​

Answer 1

Correct Question :-

• A boy of mass 55 kg runs up a flight of 40 stairs each measuring 0.15m in 15s . calculate the gain in potential energy of the body taking g as 10 ms and Find the Power in kilowatt and Horse Power

Given:-

• Mass of Body = 55kg

• Number of Stairs = 40

• Height of each Stairs = 0.15m

• Total Time = 15s

• Acceleration due to gravity = +10m/s

To Find:-

• The Gain in Potential Energy.

Formulae used:-

• P.E = mgh

• gain in Potential Energy = Final P. E - Initial P. E.

• Power = Energy/Time Taken

Where,

• m = Mass
• g = Acceleration due to gravity
• h = Height.

Now,

• → Height reached = No. of stairs × Length if each stairs

• → Height reached = 40 × 0.15

• → Height reached = 6m

Therefore,

→ Initial P. E = 0 ( As it was on ground )

→ Final P. E = mgh

→ Final P. E = 55 × 10 × 6 = 3300J

Hence, Gain in Potential energy is → 3300 - 0 = 3300J

Now,

→ Power = Energy / Time Taken

→ Power = 3300/15

→ Power = 220w

Now,

→ Power in Kw = 220/1000 ( 1kw = 1000w)

→ Power in Kw = 0.22Kw

→ Power in Hp = 220/746 ( 1Hp = 746w)

→ Power in Hp = 0.29Hp

Hence, The Power in kw and Hp is 0.22kw and 0.29Hp.