I just created a vacuum in a cup when doing the dishes?

  • Context: High School 
  • Thread starter Thread starter riskybeats
  • Start date Start date
  • Tags Tags
    Vacuum
Click For Summary

Discussion Overview

The discussion centers around the phenomenon of creating a vacuum in a cup while doing the dishes, specifically exploring the mechanisms behind the hissing sound and resistance experienced when removing the cup from a paper cloth. The scope includes experimental observations and theoretical explanations related to thermodynamics and air pressure changes.

Discussion Character

  • Exploratory, Technical explanation, Experimental/applied

Main Points Raised

  • One participant describes the experience of hearing a hissing noise from a cup that was placed mouth down on a paper cloth, suggesting a vacuum was created.
  • Another participant proposes that the hot air inside the cup cooled as the cup itself cooled, leading to a decrease in air volume and the formation of a vacuum, which is described as a common occurrence.
  • A third participant expresses enthusiasm for science and acknowledges the phenomenon.
  • A fourth participant suggests a related experiment involving a milk or juice container to demonstrate similar vacuum effects through temperature changes and air pressure variations.

Areas of Agreement / Disagreement

Participants appear to agree on the basic mechanism of cooling air leading to a vacuum, but there is no explicit consensus on the details or implications of the phenomenon. The discussion includes both agreement on the observed effects and suggestions for related experiments.

Contextual Notes

Some assumptions about the conditions under which the vacuum was created are not fully explored, such as the specific temperatures involved and the properties of the materials used. The discussion does not resolve the exact nature of the vacuum formation process.

Who May Find This Useful

Individuals interested in thermodynamics, experimental physics, or those looking for simple demonstrations of air pressure and vacuum concepts may find this discussion useful.

riskybeats
Messages
17
Reaction score
0
I want to know the mechanism behind this. I folded a paper cloth (may of been of the bounty kind), and put my wet cups on there mouth down. I heard a hissing, and I thought I may have left the stove on. I followed the noise to the cup, and noticed it was hissing like crazy. I tilted the cups mouth off of the cloth, and met quite a bit of resistance. When I got it off, it made the 'pop' noise of a vacuum being destroyed.

Any theories on how this happened?
 
Physics news on Phys.org
The hot cup had hot air in it. As the cup cooled the air inside cooled and dropped in volume. This is a common occurrence.
 
Awesome. Go science!

Thanks.
 
Science rocks! Welcome to Physics Forums.

You can do a similar experiment with a milk or juice container. Put about 1/2" or so of cold tapwater in the container, cap it, and shake it. The shaking helps the water cool the inside air quickly. This will create a slight vacuum, and a rectangular milk carton will be noticeably deformed.

Next, dump the water and put in 1/2" or so of hot tapwater, cap, and shake. That will heat the air, creating higher pressure in the carton.
 

Similar threads

  • · Replies 50 ·
2
Replies
50
Views
7K
  • · Replies 9 ·
Replies
9
Views
12K
  • · Replies 3 ·
Replies
3
Views
5K
Replies
11
Views
4K
Replies
16
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 36 ·
2
Replies
36
Views
7K
Replies
8
Views
4K