# Why does water offers less friction?

1. Sep 5, 2014

### Kaustubh sri

Why do water offers less friction?

My attempt
as water friction is less than air

can anybody tell me that i am right or not

2. Sep 6, 2014

### Orodruin

Staff Emeritus
It should be relatively clear that (liquid) water has higher viscosity than air. Just try to drag your arm through water and then through air. Which offered less resistance?

3. Sep 6, 2014

### Kaustubh sri

Ok then tell me that if someone is swimming at the surface of water he/she get high friction while during inside water it doesn't.Why?

4. Sep 6, 2014

### RGEmpress

I have a certain interest in this as well. I think viscosity is something akin to thickness of a fluid, and from experience, it is a lot easier and faster to move in the air than in the water.

5. Sep 6, 2014

### Staff: Mentor

A submarine uses much less fuel when travelling on the surface of calm water than when fully submerged, for the same speed.

6. Sep 6, 2014

### Orodruin

Staff Emeritus
7. Sep 6, 2014

### CWatters

Google found this on the submarine issue..

Last edited by a moderator: May 6, 2017
8. Sep 6, 2014

### CWatters

Sometimes water increases friction. Sometimes water reduces friction. It depends on the situation. Can you expand the question?

9. Sep 6, 2014

### HallsofIvy

Staff Emeritus
Water offers less friction than what?

If you are referring to simple motion through water or air, water does NOT "offer less friction".

Perhaps you are referring to "slipping" on a wet surface?

10. Sep 6, 2014

### SteamKing

Staff Emeritus
If this were true, we'd be flying airplanes underwater.

11. Sep 6, 2014

### AlephZero

If you are swimming at the surface, you generate waves. Ignoring the "splashing" effect of arms or legs entering or leaving the water, there is a large increase in the resistance force when an object reaches a critical speed which depends mainly on its length, because it is effectively traveling "uphill" trying to climb up the bow wave it generates in front of it. A boat with a high power engine, or a sailing boat in a strong wind, can get "on top of" its bow wave and is then effectively traveling down hill with the front of the hull completely out of the water, until it has to slow down.

Apparently ducklings can do this to escape from predators quickly, even if human swimmers can't. http://jeb.biologists.org/content/198/7/1567.full.pdf

12. Sep 6, 2014

### RGEmpress

Loons ((the state birds of Minnesota (US)) are really good at that! I don't know what their favorite fish is, (too personal to ask a Loon) - read my intro for reference to that one! - but I think this wave interference thing is what Kaustubh sri was speaking of. :-)

13. Sep 6, 2014

### Kaustubh sri

Thanx to every one helping me in the que.

14. Sep 7, 2014

### CWatters

What was the question?

15. Sep 7, 2014

### vela

Staff Emeritus
If I were grading this question, you'd get a 0 for that answer. You're essentially saying "water has less friction [than air] because it has less friction than air." It's not an explanation; you're just repeating the question as the answer.

16. Sep 7, 2014

### Student100

Should the term friction even be used in the context of the discussion?

17. Sep 7, 2014

### Kaustubh sri

Dear @vela i was only asking that i am right or not

18. Sep 7, 2014

### vela

Staff Emeritus
I know. I'm pointing out that you're not answering the question. It's like if you were asked why the sky is blue, and you answer, "because it's blue!" It's not an explanation. You're just merely restating the question in statement form.

Q: Why is there less friction?
A: Because there's less friction.

Can you not see that?

19. Sep 7, 2014

### Kaustubh sri

Sorry if it hurts you but i didn't mean that you thought about

20. Sep 7, 2014

### vela

Staff Emeritus
I'm simply pointing out that you're making a very common mistake students make when they think they're answering a question but they're in fact not doing so. I assumed you were here to learn, but apparently not. If you don't care, it's no skin off my back.