Question

Ur
(i) A man whose mass is 55 kg climbs to height of 40 m in 40 seconds. Find the power consumed by man.
(ii) If an electric bulb of 60 W is lighted 10 hours daily, Find electrical energy comsumed in 30 days. ​

Answer 1

Answer: 1) Given :

Mass of man = 50 kg

No of steps = 20

Time taken = 40 s

Height of each step= 25 cm=0.25 m

To find :

Power of the man

Solution :

⇒ The total height of the man = No of steps x Height of each step

⇒ The total height of the man = 20 x 0.25

⇒ The total height of the man = 5 m

The work done by the man will be equal to its potential energy.

Hence,

here ,

m = mass

g= acceleration due to gravity

h = height

⇒ W = 50 x 10 x 5

⇒ W = 2500 J

As per the formula,

here,

P = power

W = work

t = time

⇒ P = 2500 / 40

⇒ P = 62.5 W

The power of the man is 62.25 W.

2) E = P*T

100*3= 300WH in one day

300*30 = 9000WH (9KWH) in 30 days

4*60*2= 480WH in one day

30*480= 14400WH(14•4KWH) in 30

days

TOTAL ENERGY= 9+14•4= 23•4KWH

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