Question

A boy of mass 50 kg runs up a staircase of 45 steps in 9 s. If the height of each step is 15 cm, find his power. Take g = 10 m s 2​

Answer 1

Answer:

Given:-

→ Mass of the boy = 50 kg

→ Number of steps in the staircase = 45

→ Height of each step = 15 cm

→ Value of 'g' = 10 m/s²

To find:-

→ Power of the boy.

Solution:-

Total height climbed by the boy :-

= 45 × 15cm

= 675 cm

= 6.75 m

________________________________

Now, we know that :-

P = mgh/t

Where :-

• P is the power.

• m is mass of the body.

• g is acceleration due to gravity.

• h is height.

• t is time taken.

Substituting values, we get :-

⇒ P = 50×10×6.75/9

⇒ P = 3375/9

⇒ P = 375 W

Thus, the power is 375W .

Some Extra Information:-

• Power of a machine is defined as the

rate of work done by a machine. It is a

scalar quantity.

• S.I. unit of power is Watt(W). Another

unit of power is Horse Power (HP).

• If work done by a machine is 1 Joule in a

time of 1 second, then power of the

machine is 1 Watt.

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Explanation:

Answer 2

Answer:

A boy of mass 50 kg runs up a staircase of 45 steps in 9 s. If the height of each step is 15 cm, find his power. Take g = 10 m s 2