list 10 situations from the surroundings that show air exerts pressure
Answers
Explanation:
1. When air is pumped inside a balloon, it expands in size. This shows that the air inside exerts pressure on the walls of the balloon.
2. A sealed packet of chips swells up in the mountains. This is because the atmospheric pressure at higher altitudes is less whereas the packet is filled with gas at normal atmospheric pressure. It therefore swells up in the mountains, as the pressure inside is more than the atmospheric pressure.
Water Glass Trick. Fill a cup one-third with water. Cover the entire mouth with an index card. Holding the card in place, take the cup to the sink and turn it upside down. Remove your hand from underneath. Voilà! Because the water inside the cup is lighter than the air outside, the card is held in place by about 15 pounds of force from the air pushing up, while the force of the water pushing down is only about one pound of force.
Fountain Bottle. Fill a 2-liter soda bottle half full of water. Take a long straw and insert it in the mouth. Wrap a lump of clay around the straw to form a seal. Blow hard into the straw—then stand back. Your blowing increases the air pressure inside the sealed bottle. This higher pressure pushes on the water and forces it up and out the straw.
Ping-Pong Funnel. Put a ping-pong ball inside the wide part of a funnel and blow hard into the narrow end. Why doesn’t the ball pop out? As you blow into the funnel, the air moves faster and lowers the air pressure underneath the ball. Because the air pressure is higher above the ball than below it, the ball is pushed down into the funnel—no matter how hard you blow or which direction you point the funnel.
The Million Dollar Bet. Take an empty water or soda bottle and lay it down horizontally on a table. Roll a piece of paper towel into a small ball about half the size of the opening. Tell a friend you’ll pay $1 million if he or she can blow the ball into the bottle. Don’t worry about losing money because this is impossible. No matter how hard someone blows to try to force more air into the bottle, there's no room for it, so it will flow right out, pushing away the paper ball.
Blow Balloons. Blow up two balloons and attach a piece of string to each. Hold one balloon by the string in each hand and position the two balloons so that they are at your nose level and 6 inches apart. Blow hard into the space between the balloons. This lowers the air pressure. The pressure of the surrounding air is now higher and it will push the balloons together.
Materials Required: tumbler, water, square cardboard piece
Method: Fill up the tumbler with water up to the brim. Cover it with cardboard piece and turn the glass upside down. Slowly remove your hand.
Observation: Cardboard does not fall and water stays in the glass.
Inference: air pushes the cardboard up and prevents it from falling.
Activity II
Materials Required: plastic bottle with cap, hot water, cold water
Method: Pour hot water into the plastic bottle. Empty the bottle and put the cap tightly. Pour some ice-cold water on it.
Observation: The bottle will get de-shaped.
Inference: The air from the bottle expands as it becomes hot. When it is cooled, air contracts. The outside air has more pressure and it crushes the bottle.
Some daily life experiences that show that air exerts pressure
You find it easier to row the boat when the wind is blowing behind you.
The wind coming from the back help in flying kite.
When we suck from the straw, the liquid rises in it.
The medicine enters the syringe when a piston is pushed out.
High-speed winds are accompanied by reduced air pressure. Let us now perform certain experiments that will show that high-speed winds reduce the air pressure.
Activity III
Materials Required: Two balloons
Method: Blow the balloons and tie string to it. Hang them 10 – 12 cm apart on a rim. Blow air in between the balloons.
Observation: The balloons will move closer.
Inference: The air pressure between the balloons is reduced due to more speed. Air moves from higher pressure to lower pressure bringing the balloons closer.
- Materials Required: tumbler, water, square cardboard piece
Method: Fill up the tumbler with water up to the brim. Cover it with cardboard piece and turn the glass upside down. Slowly remove your hand.
Observation: Cardboard does not fall and water stays in the glass.
Inference: air pushes the cardboard up and prevents it from falling.
- Materials Required: plastic bottle with cap, hot water, cold water
Method: Pour hot water into the plastic bottle. Empty the bottle and put the cap tightly. Pour some ice-cold water on it.
Observation: The bottle will get de-shaped.
Inference: The air from the bottle expands as it becomes hot. When it is cooled, air contracts. The outside air has more pressure and it crushes the bottle.
- You find it easier to row the boat when the wind is blowing behind you.
- The wind coming from the back help in flying kite.
- When we suck from the straw, the liquid rises in it.
- The medicine enters the syringe when a piston is pushed out.
- Cycling against the direction of the wind, it is difficult to.....this show air exerts pressure.
- Materials Required: Two balloons
Method: Blow the balloons and tie string to it. Hang them 10 – 12 cm apart on a rim. Blow air in between the balloons.
Observation: The balloons will move closer.
Inference: The air pressure between the balloons is reduced due to more speed. Air moves from higher pressure to lower pressure bringing the balloons closer.
- Materials Required: Bottle, crumpled piece of paper
Method: Crumple a small piece of paper into a ball of a size smaller than the mouth of an empty bottle. Hold the empty bottle on its side and place the paper ball just inside its mouth. Now try to blow on the ball to force it into the bottle.
Observation: The paper does not move inside.
Inference: The air pressure at the mouth of the bottle is reduced due to more speed. This forces the air out from the bottle. This prevents the crumpled paper ball to move inside.
hope it helps........