The Effect of Temperature on Air Pressure
Length: 1294 words (3.7 double-spaced pages)
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My project consists of a series experiments to determine the effect of air pressure in a given environment at various temperatures. The experiments I chose to conduct are:
1) Heat an ordinary pop can on a hot plate and then putting the can upside down in cold water to see the effect of a fast change in temperature.
2) Partially full milk jug with hot water, put the cap on tightly, and let it sit for one hour to see the effect of a slow change in temperature.
3) Setting a small piece of paper on fire and then putting it inside a plastic bottle. Before the flame goes out, a pealed hard-boiled egg will be placed over the opening.
The problem is to determine the effects of air pressure at different temperatures. Since we cannot see air, we will attempt to determine if air exerts a force?
My hypothesis for:
1) the experiment with the pop can is that the can will crush because of a drastic change in temperature.
2) the experiment with the milk jug and the hot water is that the milk jug will remain the same.
3) the experiment with the egg and the bottle is that the egg will not be sucked in the bottle.
For the first experiment the procedure is:
1) Heat an ordinary pop can on a hot plate.
2) After about fifteen minutes take the can off the hot plate and put it upside-down in a pan of cold water.
3) Record my observations on a piece of paper.
4) Write my conclusions in my science fair logbook.
For the second experiment my procedure is:
1) Get an empty gallon milk jug at room temperature.
2) Heat to water to just before the boiling point on a hot plate.
3) Fill the milk jug about quarter of the way with hot water.
4) Put the lid on tightly
5) Wait one hour and record my observations and conclusions.
For the third experiment my procedure is:
1) Get a medium sized bottle.
2) Peel a hard boiled egg.
3) Light a small piece of paper on fire and put it inside the bottle.
4) Before the flame goes out put the pealed egg over the opening of the bottle.
5) Record my observations on a piece of paper.
6) Write my conclusions in my science fair logbook.
02/06/99- I conducted the experiment on the pop can.
After 15 minutes, I turned the can upside down and put it in the cool water. There was a loud popping sound while the can crushed. The can only crushed in the middle. There are some sharp edges where the can did not seem to crush in all the way. The can cooled down a great deal after I put it in the water and it crushed. The can was partially filled with water when I took it out of the water.
I think the can crushed because there was a great difference in air pressure. The air molecules expanded from the heat of the can. The opening at the top of the can allowed the expanding molecules to escape. This kept the inner and outer pressure equal. When the can was put into the water, heat was taken away quickly. This caused the molecules to cool and contract. Because the opening of the can was under water, no air molecules could replace the volume of the expanded molecules. This caused the pressure inside the can to be less than the pressure inside. This caused the can to collapse. The can was partially filled with water because the warm air cooled quickly and shrunk, which created a vacuum that, sucked the water in the can. The can did not crush all the way because the water filled up some of the space in the can. The air contracted when it was cooled so there was less air pressure inside the can, which made it collapse.
I can relate the can to our atmosphere. The heated can had high pressure and the water had low pressure just like a storm caused by high and low pressure systems. The popping sound can be related to thunder. In a real storm instead of the can crushing there would be thunder.
02/06/99-I conducted the air pressure experiment on the milk jug.
Before pouring the hot water into the milk jug it had the shape of an ordinary milk jug at room temperature. After the hot water was pored into the jug, it was difficult to put the lid on because it was extremely hot. After the lid was on the milk jug started to expand right away. After a minute, it began to slow and then began to collapse. Over the next hour the jug slowly collapsed even more. When the hour was up, the jug was collapsed more than at the beginning but not all the way.
Before putting the water in the jug the pressure inside and outside the jug were equal because the jug was at room temperature. After I put the top on the milk jug it started to expand. This happened because the water in the jug was hot and this caused pressure to increased. Because the cap was on the bottle, the heat and pressure had no where to escape causing the sides to expand. As the water cooled off the pressure lessened, which made the sides of the jug began to collapse. As the water inside the jug cooled more and the air pressure lessened it created extra space as the molecules cooled. After about an hour the jug did not collapse anymore because the pressure inside and outside were equal once again.
02/06/99- I conducted the experiment the egg and the bottle.
After the paper was light on fire the egg was set on top of the opening. After about 10 seconds the hard-boiled egg appeared to get pulled in the Tropicana Twister bottle. The center of the egg started to rip slightly exposing the yolk. The flame from the paper went out when the egg was about half way pulled in. The egg fell to the bottom of the bottle with a plop. After the egg fell smoke came up from the bottle.
Before lighting the paper on fire the air pressure inside and outside the bottle were the same. The burning paper inside the bottle used most of the air inside the bottle. This reduced the pressure inside the bottle creating a type of vacuum. The air from outside the bottle was trying to get inside the bottle, which pushed the egg inside the bottle. At the same time, the vacuum inside the bottle was trying to suck the egg in. When the egg fell in the bottle the pressure became once again equal.
Air pressure is the force exerted on you by the weight of tiny air particles(air molecules). Although air molecules are invisible, they still have weight and take up space. The molecules expand and contract as temperatures increase and decrease. When the molecules are kept in confined space they exert pressure that may be greater than or less than the pressure outside the container. This causes the container to expand or contract because of the pressure inside.
As determined by the experiments, temperatures a great effect on air pressure. As the temperature increases, so does the air pressure. As the temperature decreases, so does the air pressure. When allowed to cool, the air pressure will eventually reach an equal pressure to the pressure in that area. This information could be useful in the study of meteorology, thermodynamics, and in engineering.