A certain man A does 450 J of work in 5 s and another man B does 240 J of
work in 3 s.
(a) Who has more power?
(b) Find the ratio of the power delivered by A to that delivered by B.
Answers
Explanation:
power= work done/ time
power of 1st person= 450 J / 5s
= 90 J/s
power of 2nd person= 240 J/ 3s
= 80 J/s
a) 1st person has more power
b) 90:80 = 9:8
Answer:
Let's understand about power first!
It is common experience that different persons complete a given work in different times. A person doing work quickly is said to be stronger but a person who does some work in a longer time is said to be weaker. In this context, we define the term power, which is a measure of rate of doing work.
Power:
The power of a person/machine/system is defined as its rate of doing work.
If W work is done in the time t, then the power P is given as:
✭ Power, P = Work, W/ Time, t ✭
Let's come to question now...
As we are provided with the work and time of both men A and B. We will find the power of both men A and B separately and then compare them to find out who has more power. After that we will find out the ratio of their powers.
Let's find out...✧
a.)
➛ Work done by man A, W = 450 J
➛ Time taken, t = 5s
✭ Power, P = Work, W/ Time, t ✭
Putting the values in the formula, we have:
➛ P = 450/5
➛ P = 90 W
∴ Power of man A = 90 W
➛ Work done by man A, W = 240 J
➛ Time taken, t = 5s
✭ Power, P = Work, W/ Time, t ✭
Putting the values in the formula, we have:
➛ P = 240/3
➛ P = 80 W
∴ Power of man B = 80 W
Comparing the powers of both we find that,
90 W > 80 W
Power of man A > Power of man B
∴ Man A has more power.
b.)
➛ The ratio of the power delivered by A to that delivered by B = Power of man A/Power of man B
➛ The ratio of the power delivered by A to that delivered by B = 90/80
➛ The ratio of the power delivered by A to that delivered by B = 9/8
➛ The ratio of the power delivered by A to that delivered by B = 9:8
∴ The ratio of the power delivered by A to that delivered by B is 9:8
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