
The unit of power is:
A) Watt per second
B) Joule
C) Kilojoule
D) Watt
Answer
510.6k+ views
1 likes
Hint: Power is a ratio of work done to the time taken. It is defined as the time rate at which work is done or energy is transferred.
Complete step by step solution:
We know that Power is defined as the time rate at which work is done or energy is transferred.
If is the amount of work done in a time t then the average power is given by the ratio of the work done W to the total time t.
Therefore, power is given by the formula
Where is the power, is the work done and is the time.
We are interested to find out the SI unit of power.
The work is given as,
Thus, the SI unit of work done is the Joule, and the SI unit of time is second.
Therefore, the unit of power will be,
Which can be also written as Joule per second or
But is known as the Watt (W).
Thus, if we look at the options given, the option (A),(B) and (C) does not represent the unit of power.
The unit of power is Watt(W). Hence, the Correct option is (D).
Additional information:
If is the work done in an extremely small time interval , the instantaneous power is,
Since ,
Then
We know that, is the velocity of a body.
Thus, we have,
Therefore, power can also be defined as the dot product of force and velocity.
Where is the instantaneous velocity when the force applied is .
We know that The SI unit of power is the watt (W).
If one joule of work is done per second, the power is one watt.
Kilowatt-hour (kWh) is a large practical unit of work and energy. It is used particularly in calculating the consumption of electrical energy. The electricity bill carries the energy consumption in units of kWh. A kilowatt-hour is equal to the total quantity of energy consumed or work done in one hour at a rate of thousand joules per second.
Note:
(i) Power can also be defined as the dot product of force and velocity.
(ii) Power is a scalar quantity.
Complete step by step solution:
We know that Power is defined as the time rate at which work is done or energy is transferred.
If
Therefore, power is given by the formula
Where
We are interested to find out the SI unit of power.
The work is given as,
Thus, the SI unit of work done is the Joule, and the SI unit of time is second.
Therefore, the unit of power will be,
Which can be also written as Joule per second or
But
Thus, if we look at the options given, the option (A),(B) and (C) does not represent the unit of power.
Additional information:
If
Since
Then
We know that,
Thus, we have,
Therefore, power can also be defined as the dot product of force and velocity.
Where
We know that The SI unit of power is the watt (W).
If one joule of work is done per second, the power is one watt.
Kilowatt-hour (kWh) is a large practical unit of work and energy. It is used particularly in calculating the consumption of electrical energy. The electricity bill carries the energy consumption in units of kWh. A kilowatt-hour is equal to the total quantity of energy consumed or work done in one hour at a rate of thousand joules per second.
Note:
(i) Power can also be defined as the dot product of force and velocity.
(ii) Power is a scalar quantity.
Latest Vedantu courses for you
Grade 11 Science PCM | CBSE | SCHOOL | English
CBSE (2025-26)
School Full course for CBSE students
₹41,848 per year
Recently Updated Pages
Master Class 9 General Knowledge: Engaging Questions & Answers for Success

Master Class 9 English: Engaging Questions & Answers for Success

Master Class 9 Science: Engaging Questions & Answers for Success

Master Class 9 Social Science: Engaging Questions & Answers for Success

Master Class 9 Maths: Engaging Questions & Answers for Success

Class 9 Question and Answer - Your Ultimate Solutions Guide

Trending doubts
Difference Between Plant Cell and Animal Cell

What is the Full Form of ISI and RAW

Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

Discuss what these phrases mean to you A a yellow wood class 9 english CBSE

Name 10 Living and Non living things class 9 biology CBSE

Name the states which share their boundary with Indias class 9 social science CBSE
