Question

a girl of mass 60kg runs up a flight of 50 stairs, each measuring 20cm, in 60 seconds. Calculate the power of the girl​

Answer 1

Given :

• Mass of the girl = 60 kg
• Total Number of stairs = 50
• Height of each one = 20 cm
• Time taken = 60 sec

To Find :

• Power of the girl

Solution :

Height of each stair = 20 cm = 0.2 m

Total height of the staircase = Number of stairs × height of each stair = 50 × 0.2 = 10 m

Expression for Power is given by ,

$\\ : \implies \sf \: P = \frac{mgh}{t}$

We have ,

• m = 60 kg
• g = 9.8 m/s²
• t = 60 sec
• h = 10 m

Now by substituting the values we get ;

$\\ : \implies \sf \: P = \frac{(60 \: kg)(9.8 \: ms {}^{ - 2} )(10 \: m)}{(60 \: s)}$

$\\ : \implies \sf \: P = \frac{600 \: kgm {}^{2} (9.8)}{60 \: s {}^{ - 3} }$

$\\ : \implies \sf \: P = \frac{5800}{60} \: kgm {}^{2} {s}^{ - 3}$

$\\ : \implies{\underline{\boxed{\sf { \: P = \:98 \: W }}}}$

Hence , The Power of the girl is 98 W.

Answer 2

Heya !

Given:-

• Mass of the girl = 60 kg
• Total Number of stairs = 50
• Height of each one = 20 cm (0.2m)
• Time taken = 60 sec

To find:-

• Power of the girl

Knowledge required :-

• P = mgh/t

where,

• m = mass
• g = acceleration due to gravity (which we take 10m/s²)
• h = height (total height = 50×0.2 = 10m)
• t = time

Solution:-

putting the values in the formula

P = $\frac{60 \times 10 \times 10}{60} = 100 \:$

Hence, the power is 100W.

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Hope it helps ⭐⭐⭐