A. Give reasons for the following.
1 Needles have a sharp point.
2. A balloon bursts when too much air is blown into it.
3. We have to put an effort to push down an open and inverted glass bottle into a
bucket full of water.
4. Atmospheric pressure reduces as we go up in altitude.
Answers
Answer:
1) Needle are meant for piercing things. So, the pointed tips allows the needle to exert high pressure on the surface to be pierced.
2. When we blow air into a balloon, it expands due to the elasticity of the rubber.
But after a point, the rubber is expanded to its maximum point and cannot be stretched further.
If the balloon is blown beyond this point, it will burst because there will be no space for the rubber to accommodate the air.
3. You will find it difficult to push deeper and deeper. This indicates that water exerts a force on the bottle in the upward direction. The upward force exerted by the water goes on increasing as the bottle is pushed deeper till it is completely immersed.
4.At higher elevations, there are fewer air molecules above a given surface than a similar surface at lower levels. Since most of the atmosphere's molecules are held close to the earth's surface by the force of gravity, air pressure decreases rapidly at first, then more slowly at higher levels.
Answer:
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