If you take an empty cup and submerge it upside down in water it remains empty while underwater. Why is this? Try to explain what exactly is happening, not just "pressure difference."
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If you take an empty cup and submerge it upside down in water it remains empty while underwater. Why is this? Try to explain what exactly is happening, not just "pressure difference."
The air inside the cup exerts pressure in all directions. This pressure pushes down on the surface of water, as the cup is lowered into water. The water pressure increases as the depth increases.
If you use a clear glass, you will see surface of the water inside the inverted glass. As the glass is lowered, the surface of the water, inside the glass will rise. The water pressure is greater than the air pressure, so, the water pushes up on the air.
Fun Lab
You need an empty aluminum pop can, a hot plate or stove, and wide frying pan or bucket filled with cold water.
You need tongs to hold the pop can
.
I pour 5 ml of water into an aluminum pop can. Heat the can until steam is coming out of hole in the can. Use the tongs to QUICKLY invert the pop can and place the top of the pop can in the water.
“BANG”, “Splash” what a mess!!
The cold water will condense the steam in the pop can. This reduces the pressure inside the pop can. Now the pressure outside the can is much greater than the pressure inside the can. So, the can collapses inward. When you lift the can out of water, water will flow out of the hole.
Fun Times
I found the video below
http://www.youtube.com/watch?v=QVayky_b-…
I have done this at home, on my kitchen stove. I inverted the steaming can and quickly carried it to the sink full of water.
See an explanation at the web site below!
http://www.stevespanglerscience.com/expe…
I hope this helps you!
The air inside the cup exerts pressure in all directions. This pressure pushes down on the surface of water, as the cup is lowered into water. The water pressure increases as the depth increases.
If you use a clear glass, you will see surface of the water inside the inverted glass. As the glass is lowered, the surface of the water, inside the glass will rise. The water pressure is greater than the air pressure, so, the water pushes up on the air.
Fun Lab
You need an empty aluminum pop can, a hot plate or stove, and wide frying pan or bucket filled with cold water.
You need tongs to hold the pop can
.
I pour 5 ml of water into an aluminum pop can. Heat the can until steam is coming out of hole in the can. Use the tongs to QUICKLY invert the pop can and place the top of the pop can in the water.
“BANG”, “Splash” what a mess!!
The cold water will condense the steam in the pop can. This reduces the pressure inside the pop can. Now the pressure outside the can is much greater than the pressure inside the can. So, the can collapses inward. When you lift the can out of water, water will flow out of the hole.
Fun Times
I found the video below
http://www.youtube.com/watch?v=QVayky_b-…
I have done this at home, on my kitchen stove. I inverted the steaming can and quickly carried it to the sink full of water.
See an explanation at the web site below!
http://www.stevespanglerscience.com/expe…
I hope this helps you!