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प्रश्न
What is energy?
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उत्तर १
The ability or capacity to do work is called energy.
उत्तर २
Energy is defined as the capacity to do work. S.I unit of work is Joule.
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संबंधित प्रश्न
Write true or false of the following statement.
Potential energy changes into kinetic energy when it is put to use
Fill in the blank
An electric fan converts electrical energy into ______ energy.
Fill in the blank
Cooking gas converts _______ energy into heat energy.
Fill in the blank
The S.I.unit of energy is ______
Match the following columns
| COLUMN A | COLUMN B |
| 1. Running water | 1. heat energy |
| 2. Burning | 2. vibrations |
| 3.Energy | 3.atom bomb |
| 4.Sound energy | 4.kinetic energy |
| 5.Nuclear energy | 5.joule |
Select the correct alternatives
When we rub our hands
Select the correct alternatives
The correct statement is
State the unit of energy and define it.
State two factors on which the potential energy of a body at a certain height above the ground depends.
Match the following:
| Column A | Column B |
| (a) Needle | (1) class II lever |
| (b) Doorknob | (2) inclined plane |
| (c) Ramp | (3) Class I lever |
| (d) Lemon crusher | (4) Wheel and axle |
| (e) Seesaw | (5) wedge |
Answer the following in short.
What do you understand by the term efficiency of a machine’?
Give a reason for the following.
The efficiency of a machine is always less than 100%.
Derive the relation between commercial unit of energy (kWh) and SI unit of energy (joule).
A certain household consumes 650 units of electricity in a month. How much is this electricity in joules?
- Take two aluminium channels of different lengths.
- Place the lower ends of the channels on the floor and hold their upper ends at the same height.
- Now take two balls of the same size and weight and release them from the top end of the channels. They will roll down and cover the same distance.
- At the moment of releasing the balls, which energy do the balls have?
- As the balls roll down which energy is converted into which other form of energy?
- Why do the balls cover the same distance on rolling down?
Note: The question is wrong. It should be "Why do the balls cover the same distance after rolling down"? - What is the form of the eventual total energy of the balls?
- Which law related to energy does the above activity demonstrate? Explain.
The capacity that an object has for doing work is called ______.
Running water possesses ______.
Which one of the following requires wind energy?
Find out the form of energy possessed by the following thing.
A rock on the top of a hill
When a body falls freely towards the earth, then its total energy
