# Water surface rise or not

1. Sep 6, 2014

### Kaustubh sri

When we look in the aquerium , the fish moves from here to there but there is no disturbance at the surface of water . Why is it so?

My attempt
Actually I think that this problem is due to permiability of water. Am I right or wrong?

2. Sep 7, 2014

### CWatters

permeability of water? Do you mean the compressibility of water? It's not that.

If the fish is deep enough the disturbance at the surface has a small large radius. Water also flows quickly so it's self levelling.

3. Sep 7, 2014

### Kaustubh sri

What do u mean by small large radius

4. Sep 7, 2014

### SteamKing

Staff Emeritus
What do you mean by 'the permeability of the water'?

5. Sep 7, 2014

### Kaustubh sri

I mean to say water flux

6. Sep 8, 2014

### CWatters

Sorry I made a typo. I meant

If the fish is deep enough the disturbance at the surface has a large radius.

7. Sep 8, 2014

### Kaustubh sri

But if the fish is at the near the surface than

8. Sep 8, 2014

### CWatters

http://www.evols.org/mediawiki/images/thumb/e/ed/BL-06-1-streamlined.png/250px-BL-06-1-streamlined.png [Broken]

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

### olivermsun

There is indeed a disturbance at the surface of the water; it is usually negligibly small because the density difference between air and water is so big.

10. Sep 8, 2014

### HallsofIvy

Staff Emeritus
Because of the viscosity of water, any time water moves, there is a loss of energy. If the fish is deep enough under the water, the energy will have dissipated by the time the disturbance reaches the surface.

11. Sep 8, 2014

### Kaustubh sri

Thanx Cwatters and olivermsun I got it