#$&*
course Phy 242
January 28 around 11:50am.
Brief Bottle Experiment 1cStarting with the cap in place on an empty bottle, siphon water from an adjacent full bottle. Allow the siphon to run a few minutes until the water levels in the two bottles stabilize.
Estimate the percent change in the volume of the air in the capped bottle.
****
20%
#$&*
Estimate the percent change in the number of molecules in the air within the capped bottle.
****
Wouldn’t this be 20% also?! I know that as the number of molecules of air decrease, the air pressure decreases.
@&
Air can't get into or out of the capped bottle, so the number wouldn't change.
*@
#$&*
Estimate the percent change in the volume of the water in the open bottle.
****
20%
#$&*
What do you think is the percent change in the air pressure in the capped bottle?
****
Since there’s less air in the capped bottle now, there would be less pressure?!
@& There's less volume, but the same amount of air.
What are the implications for the frequency and energy of the collisions of the gas molecules with the walls of the container?*@
#$&*
What is the difference in the two fluid levels?
****
When I siphoned the 2 bottles, I squeezed the empty capped bottle, while the tube is in the full open bottle. I ended up getting about 20% of the capped bottle full of water, while the open bottle still has 80% water in it. I HOPE I siphoned it right!
@& I'm glad you explained that. This explains how people are getting high percentages.
I intended that you would start the siphpon, then cap the bottle. However I didn't say that.
So you did squeeze air out of the bottle, and the number of molecules did decrease.
Unfortunately you weren't able to measure the amount of air squeezed out of the bottle, as you pretty much note below.*@
#$&*
What is the percent change in the number of air molecules in the capped bottle?
****
I still am not sure about “air molecules” and how to calculate them.
#$&*
Raise the open bottle as high as possible without disturbing the capped bottle. Allow time for the water levels in the two bottles to stabilize.
What percent of the volume of the capped bottle do you now estimate is occupied by water?
****
30%, like I said, I hope I did this right.
#$&*
Estimate the percent change in the number of molecules in the air within the capped bottle.
****
?
#$&*
By what percent do you estimate the pressure in the capped bottle exceeds the original pressure (i.e., the pressure when the bottle was first capped)?
****
Since there is less air in the capped bottle now, I’m thinking there is more pressure. Would this be 30% more?!
#$&*
What percent of the uncapped bottle do you estimate is now occupied by air?
****
30%
#$&*
What is the difference in the two water levels?
****
The capped bottle has about a third of the water in the open bottle.
#$&*
Return the uncapped bottle to the tabletop. What happens?
What is now the difference in the two water levels?
****
The water in the opened bottle increased.
#$&*
What do you think is the pressure in the uncapped bottle as a percent of its original pressure (before the bottle was capped)?
****
More pressure.
#$&*"
@& You did use a different way of siphoning water than I was thinking about. You followed the instructions just fine.
Can you explain what happened to the pressure in the bottle after you stopped squeezing it, and how this change initiated the siphoning action?*@