Advertisements
Advertisements
प्रश्न
Give a reason for the following.
The efficiency of a machine is always less than 100%.
Advertisements
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.
APPEARS IN
संबंधित प्रश्न
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 |
- 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 ______.
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 ______.
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?
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)
