We can’t see or smell air, but it is surrounding us at all times from every direction. Have you ever had your ears pop on a plane or hiking/driving up a mountain? That’s the effect of air pressure.
Air can do something pretty powerful things! Meteorologists study the pressure of air because changing air pressure results in different types of weather. Nice, sunny weather typically goes hand in hand with high pressure & low pressure typically results in active, unsettled weather bringing cloudy days and rain.
The Power of Air
Water Bottle Filled With Water
Thumbtack / pushpin
1. Fill Jar with water
2. Place index card on top
3. Flip the bottle over with card in tact
You would expect that as you flip the jar over that water will come spilling out. Wouldn’t Gravity cause the water to rush to the floor? Not quite. Air pressure plays a role here. All of the air pushes against the card that now acts like a seal. The force of air keeps the water from spilling out! This is one way to see air pressure at work.
1. Poke a few thumbtacks into a full bottle of water with cap on.
2. Make several small holes and remove the thumbtacks.
You would think that water would spill out from the holes but that is not the case. The cap is keeping air pressure from getting into the bottle. The water stays in the bottle as the air pressure outside of the bottle acts against the water/holes. Now, take the cap off. The water rushes out where you made the holes! That’s because air is now rushing back into the bottle and forces the water out.
Egg in Bottle:
Empty 20 Oz Glass bottle (i.e. Snapple bottle)
Hard Boiled Egg
Matches / Lighter
Directions (Adult/parent needed):
1. Grab your glass jar and hard boiled egg.
2. First, light a piece of paper on fire (Adult/Parent Needed) and quickly put inside jar.
3. Immediately place your hard boiled egg onto the top of the jar
Wow! The Egg is sucked into the bottle! As the paper burns, it heats the air inside the bottle. The heated air rushes out. As the air escapes, the outside air pressure forces the egg into the bottle! By lowering the pressure inside the bottle, The egg slips in.
Water Balloon in Bottle (Adult/Parent needed):
1. Grab your glass jar and hard boiled egg
2. Light a piece of paper on fire and quickly place in jar (Adult/ Parent Needed)
3. Place your water balloon on the top of the bottle
Wow! Watch as the balloon is sucked all the way into the bottle! We need to lower the pressure in the bottle to get the balloon to slide in. We do that by heating the inside of the bottle. the heated air rushes out the top and the force of air pressure makes the balloon rush into the bottle.
Now, can we get the balloon out? Yes! We need to now increase the pressure in the bottle!
1. Place a straw into the bottle and blow
As you blow air back into the bottle that increases the air pressure. As you blow the air, pull the balloon out. The force of air pushes the balloon back out!
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Source: ABC7 Chicago