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प्रश्न
Observe the picture and put a tick (✓) if work is done and put a cross (x) if work is not done.
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उत्तर
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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
What is potential energy ? State its unit.
State two factors on which the potential energy of a body at a certain height above the ground depends.
Tick the most appropriate answer.
The force applied on a machine to do work is called the
Answer the following in a word or two or in a sentence.
Write the formula for calculating the efficiency of a machine.
A cell converts one form of energy into another form. Name the two forms.
- 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.
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?
When a body falls freely towards the earth, then its total 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)
