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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
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?
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.
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.
Select the correct alternatives
When a bulb lights up on passing current, the change of energy is
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 a word or two or in a sentence.
Write the formula for calculating the efficiency of a machine.
Give a reason for the following.
The efficiency of a machine is always less than 100%.
Define the term 'watt'.
Name the quantity whose unit is :
(a) kilowatt
(b) kilowatt-hour
What is the common name of '1 kWh' of electrical energy?
The commercial unit of energy is :
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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?
The work done on an object does not depend upon the
The weight of a person on planet A is about half that on the earth. He can jump up to 0.4 m in height on the surface of the earth. How high he can jump on planet A?
