Question

A girl of mass 40 kg runs up a staircase of 30 steps in 10 s. If the height of each step is 0.1 m, find the power developed by her. Take g = 10ms^-2

Answer 1

Explanation,

Given,

• Mass (m) of a girl = 40 kg

• Total height (h) = 30 × 0.1 m ⇒ 3 m

• Time (t) = 10 s

• Acceleration due to gravity (g) = 10 ms-²

To Find,

• The power developed by her.

Solution,

Applying power formula,

P = w/t

Where,

• P = Power
• W = Work done
• t = Time

⇒ P = mgh / t

⇒ P = 40 × 10 × 3 / 10

⇒ P = 400 × 3 / 10

⇒ P = 40 × 3

⇒ P = 120 W

Therefore,

The power developed by her is 120 W.

Answer 2

Answer:

P = Power

W = Work done

t = Time

⇒ P = mgh / t

⇒ P = 40 × 10 × 3 / 10

⇒ P = 400 × 3 / 10

⇒ P = 40 × 3

⇒ P = 120 W