Balloon in a Bottle
Can you blow up a balloon in a bottle?
Materials needed:
| two one-liter soda bottles |
| two balloons with wide openings |
| nail |
Instructions:
| Using the nail, punch a small hole in one of the bottles, about five centimeters from the bottom. |
| Insert an uninflated balloon into each bottle, stretching the opening of the balloon over the mouth of the bottle. Do you think you will be able to blow up the balloons inside the bottles? Why or why not? |
| Try blowing up the balloons. What happens? Can you explain your results in terms of air pressure? |
| Now fully inflate the balloon inside the bottle with the hole. When you are done, hold your finger over the opening. What do you think will happen when you remove your finger? Try it. |
| Inflate the balloon again, holding your finger over the hole. Now fill the inflated balloon with water. If you remove your finger, do you think the increase in air pressure as the air enters the hole will be strong enough to push the water out? Try it and see. |
The Heavy Paper
Materials needed:
| ruler |
| large sheet of paper |
| table or other flat surface |
Instructions:
Position the ruler so that about two-thirds of it is on the table and the remaining third is hanging over the edge.
| Lay the sheet of paper on the table over the ruler. |
| Hit the overhanging end of the ruler with a downward motion. |
| Can you make the paper fly into the air? |
| What happens if you change the size of the paper? |
| Explain your results in terms of pressure. |
Pressure Bottle
Materials:
| one-liter soda bottle with three small holes punched in it as shown |
| bottle cap |
| three push pins |
| large shallow pan to hold bottle |
Instructions:
| Fill the bottle with water but do not cap it. Remove the middle pin. Does any water come out? |
| Now screw the lid on tightly. Does water come out now? |
| Loosen the cap. What happens? Why does capping the bottle make a difference? |
| Replace the middle pin and refill the bottle. Cap it. Take out the middle pin and squeeze the bottle. Does water come out? |
| Squeeze hard and then lightly. How does the strength of your squeeze affect the stream of water? |
| When you stop squeezing, watch the hole carefully. What happens? Why do you think this happens? |
| Replace the middle pin and refill the bottle. Remove all three pins and the cap. How do the three streams of water differ? Make a sketch of the bottle and the streams below. |
| Watch your bottle for a few minutes. As the level of the water goes down, how do the streams change? Why do you think this happens? |
| Replace all three pins and refill the bottle. Cap it. Now remove any two of the pins. What happens? |
| Now try two other pins. Try all of the combinations. Is there any difference between taking the top and bottom pins out and taking the middle and bottom pins out? Describe the difference. What do you think causes this difference? |