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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.
संबंधित प्रश्न
Write true or false of the following statement.
A gum bottle lying on a table has no energy.
Write true or false of the following statement.
In an electric fan, electrical energy changes into the mechanical energy.
Write true or false of the following statement.
Potential energy changes into kinetic energy when it is put to use
Select the correct alternatives
When we rub our hands
State the unit of energy and define it.
What is potential energy ? State its unit.
What do you mean by conservation of mechanical energy? State the condition when does it hold.
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 |
Define the term 'watt'.
The commercial unit of energy is :
- 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.
If the energy of a ball falling from a height of 10 metres is reduced by 40%, how high will it rebound?
The capacity that an object has for doing work is called ______.
Can you tell?
What should be taken into account for measuring work?
We make useful objects from a variety of substances. Another use of substances is that we get energy from some of them.
There is a car. Its tank is full of fuel but it does not move. Why is that?
Running water possesses ______.
Find out the form of energy possessed by the following thing.
A rock on the top of a hill
Write the type of energy.
A ball is dropped from a height of 10 m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back? (g = 10 m s–2)
Define kilowatt hour.
