Question

6. A man does 200 J of work in 10 seconds and a boy does 100 ) of work in 4 seconds.
a. Who delivers more power?
b. Find the ratio of the power delivered by the man to that by the boy. ​

Answer 1

(a) Who delivers more power ? :-

Method of solving :-

Firstly finding the power of the man & the boy , and then by comparing . We can find who delivers more power .

♦ Power of man :-

→ Power = W/t

→ Power = 200/10

→ Power = 20 W

♦ Power of boy :-

→ Power = W/t

→ Power = 100/4

→ Power = 25 W

So , now

◉ Power of man < Power of boy

Hence , the boy delivers more power than the man .

(b) Ratios of the powers of the man to the boy :-

From the above question , already we found the values of the powers of the man & the boy .

Let ,

• Power of man be W
• Power of boy be W'

Now finding the ratios ,

=> Power of man : Power of boy = W : W'= 20:25

=> W : W' = 4 : 5

Hence , ratios of the powers of the man to the boy = 4 : 5

Answer 2

Answer :-

• The boy delivers more power.
• The ratio of the power delivered by the man to that by the boy is 4 : 5.

Explanation :-

To Find,

• Who delivers more power?
• Find the ratio of the power delivered by the man to that by the boy.

Solution,

Given that,

• Work done by a man = 200 J
• Time taken by the man = 10 secs

• Work done by a boy = 100 J
• Time taken by the boy = 4 secs

As we know that,

Power = W / t,

Where,

• W = Work done
• t = Time

The power of the man :-

➮ 200 / 10

➮ 20 Watt ★

The power of the man is 20 W.

The power of the boy,

➮ 100 / 4

➮ 25 Watt ★

The power of the boy is 25 W.

We got,

• Power of man = 20 W
• Power of boy = 25 W

Therefore, The boy delivers more power.

And, the ratio of the power delivered by the man to that by the boy is,

➮ 20 : 25

➮ 4 : 5 ★

Hence, the ratio of the power delivered by the man to that by the boy is 4 : 5.

More Information

• Power = Work done / Time
• 1 watt = 1 joule / 1 second
• The S.I. unit of power is Watt. It is denoted by W.