Question

A girl of mass 40 kg skips 0.20 m high 30 times a minute. Calculate the average power exerted by

her? ​

Answer 1

Given :-

Mass of the girl = 40 kg

Height skipped by the girl = 0.20 m

Number of times she skips = 30 times per min

To Find :-

The average power exerted by the girl.

Analysis :-

Firstly find the total height by multiplying the height she skips and the number of times per minute.

Then find the work done by the girl using it's respective formula.

Finally, find the power by dividing the work done and the time taken by the girl.

Solution :-

We know that,

• p = Power
• w = Work done
• t = Time
• m = Mass
• h = Height
• g = Gravity

Total height,

Height (h) = 0.20 m

No. of times skipped = 30 per min

Substituting their values,

⇒ 0.20 × 30

⇒ 6 m

Using the formula,

$\underline{\boxed{\sf Work \ done=Mass \times Gravity \times Height}}$

Given that,

Mass (m) = 40 kg

Gravity (g) = 10 m/s

Height (h) = 6 m

Substituting their values,

⇒ w = mgh

⇒ w = 40 × 10 × 6

⇒ w = 400 × 6

⇒ w = 2400 J

Using the formula,

$\underline{\boxed{\sf Average \ power=\dfrac{Work \ done}{Time \ taken} }}$

Given that,

Work done (d) = 2400 J

Time (t) = 600 sec

Substituting their values,

⇒ p = w/t

⇒ p = 2400/6

⇒ p = 400 W

Therefore, the power exerted by the girl is 400 W.