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प्रश्न
When a body falls freely towards the earth, then its total energy
पर्याय
increases
decreases
remains constant
first increases and then decreases
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उत्तर
remains constant
Explanation:
When a body falls freely towards the earth, its potential energy decreases which in turn increases the kinetic energy. Therefore, its total energy remains constant.
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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.
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 |
What is energy?
Name the commercial unit of measurement of energy.
Name two units of power bigger than watt.
How many joules are there in one kilowatt-hour?
- 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.
What energy transfer happen in a car engine?
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)
