A cork in a glass of water

  • Thread starter kath102245
  • Start date

kath102245

Why is it that when you put a cork in a glass of water, it won't float in the center?
~Kathleen
 

chroot

Staff Emeritus
Science Advisor
Gold Member
10,166
34
Because the water's surface is not flat. The water has surface tension, which tends to pull the water up along the edge of the glass. In other words, the water around the edge is higher than the water in the center. The cork seeks (via the buoyancy force) the highest position, which is at the edge.

- Warren
 

Hurkyl

Staff Emeritus
Science Advisor
Gold Member
14,845
17
You can make the cork float on the center, though, if you're clever.

Fill a glass (with cork in it) to the brim with water. Slowly add water so the water goes slightly over the brim but does not spill. You'll find the cork now floats in the middle of the glass!
 
373
2
I just tried this with a cork - It works well.


Perhaps we should have a forum (or reference links?) of interesting experiments, along with an explanation of how they work. Between us all we must know hundreds of great, but simple, experiments. I suppose that this would be hard to arrange though.....
 

Related Threads for: A cork in a glass of water

  • Posted
Replies
6
Views
614
Replies
3
Views
3K
  • Posted
Replies
7
Views
48K
Replies
2
Views
3K
  • Posted
Replies
5
Views
815
Replies
10
Views
18K
Replies
5
Views
3K
Replies
17
Views
2K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top