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प्रश्न
Give a reason for the following.
The efficiency of a machine is always less than 100%.
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उत्तर
Efficiency of a machine is always less than 100% as output energy is always less than the input energy because some energy is lost to overcome friction.
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संबंधित प्रश्न
Select the correct alternatives
When we rub our hands
Tick the most appropriate answer.
The force applied on a machine to do work is called the
- 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.
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- 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?
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Can you tell?
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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?
We make useful objects from a variety of substances. Another use of substances is that we get energy from some of them.
When we have run a long distance, we feel tired. We have to stop. Why is that?
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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Which one of the following requires wind energy?
