Question

A boy climbs a 90-meter hill in 10 minutes. His weight is 400 N. How much power does the boy have as he climbs the hill?

Power (W) = Work (J) / Time (s)
Work (J) = Force (N) x Distance (m)
Force (N) = Mass (kg) x Acceleration (m/s2)

A
60 W

B
490 W

C
600 W

D
36,000 W

Answer 1

`\huge\boxed{\sf Power = 60 \ W}`

Explanation:

Given data:

Height = h = 90 m

Time = t = 10 × 60 = 600 s

Weight = W = 400 N

Required:

Power = P = ?

Formula:

`\displaystyle Power = (Work)/(Time)`

Solution:

Here, the work is done in the form of potential energy (height involved), so we will use the formula of potential energy to find work.

Hence,

Work = Weight × Height (P.E = W × h)

Work = 400 × 90

Work = 36,000 N

Now,

`\displaystyle Power = (Work)/(Time) \\\\Power = (36000)/(600) \\\\\boxed{Power = 60 \ W}\\\\\rule[225]{225}{2}`