why is a soap bubble round???
363817
A soap bubble is spherical in shape.\n\nTo answer why a soap bubble is spherical, first we shall observe a two-dimensional phenomenon and then go to the spherical shape.\n\nConsider a rope whose ends are knotted together. Place it on the ground in any irregular shape. Equal forces are applied on each point (or small segments) of the rope so as to increase the enclosed area. Each small segment will move till the rope is in the form of a circle and the movement will be stopped after forming a circle.\n\nIf any of the force tends to move the segment in its direction, there will be exactly another force diametrically opposite to this one pulling it in the opposite direction.\nNo other shape than the circle can have this effect.\n\nIn a three dimensional view, if similar forces acting in all directions, it is not hard to visualize that the shape will be a sphere.\n\nIn a soap bubble, the air inside pushes (instead of pulling) the surface formed by soap in all directions with equal pressure.\n\n The atmospheric pressure and the surface tension of the soap bubble try to shrink the surface of the soap bubble till equilibrium is reached.
558485
It is called Total Fatty Matter. It gives the lather producing capacity of the soap. The more it is the good the soap is.
253045
Water often contains a great deal of suspended air - but it is not visable as they are very small.  When you shake the water, the little bubbles start bumping into each other, and if they are big enough, you will see them.  If they are big enough to see, they will float to the top and pop!\n\nIf you have an aerator on your kitchen sink you can get lots of bubbles from shaking water.  Water that has sat in a bottle undisturbed for a while has most of its bubbles gone.
1024555
A quick test is to set it on a "level" surface. See where the bubble is and then turn the level 180 degrees. the bubble should show the same degree of level. \n\nWith a precision level there are usually multiple marks rather than just two so you should be able to see even a minor lack of levelness on a surface and that should be repeated when you turn the level 180 degrees.\n\nI do the same thing with my cheap carpenters level when I use it to be sure it isn't out of whack.
304121
ZW88 is partly correct -- the problem is not surface tension.  The toothpicks provide nucleation sites for bubbles to form in a more controlled manner, thus preventing more catastrophic boiling.
393819
Half cup Sunlight soap, half cup water and one teaspoon of glycenrine (you can get that at the drugstore, it keeps the bubbles from popping so fast).
518623
when u swirl the water, if the object floating on it is not moving at the same speed, it would have a lower outward force. They r then pull by gravity towards the lower point... the middle of the swirling water. whichever thing slows down first, it will "drop" to the middle.\n\nI notice too that even if the thing does not float, like sugar, they r concentrated at the middle in the bottom. I think that's due to gravity too. When u swirl, water goes to the side and when the roundabout motion slows, water slowly falls back down to the middle. there's a net flow toward the middle and hence dragging the sugar to the middle.
289497
All soaps and detergents are they way they are because they're amphoteric substances. That means one end of the molecule is a fatty chain that repels water but loves nonpolar chemicals. the other end of the detergent molecule is polar and probably carries a charge. This side likes water.\n\nSo what happens is the fatty chain clings to greasy things and the polar or charged end clings to water. This brings your greasy stains closer to the water in your wash and off of your clothing.
263044
when soap is mixed with water, it increases the surface tension so that when air bubbles get underneath, cant break through the increased surface tension.
1013381
This would be an awesome inexpensive experiment. as I believe that it does with respect to the diameter of the bubble gravity attraction should be increased with respect to surface area, however this experiment should be conducted in an environment free from draft and circulating air flow.
314648
The bubbles are the same color as the soap. They are mostly air though and there is so little "soap" in a bubble they always appear clear (or white when there is a bunch of them together.
820312
Because air preasure is distributed evenly and in all directions. Notice that if you blow on a bubble it changes shape temporarily, but only as long as the preasure on it is from one side. After you stop blowing it returns to perfectly round.
196622
I pierced a candle with the needle and carefully placed the needle on water surface. It floated well. \n\nThis due to the surface tension effect.\n\nNext I did with another needle without wax coating. This time it floated once in many trials.\n\n\nNext I placed the needle on a piece of blotting paper and placed it on the surface of water. The blotting paper in few seconds went inside leaving the needle floating.
605515
It is not exactly round, just looks that way.\n\nSee webpage below for the correct shape.
478525
Everyone says that The surface tension causes the bubble to be spherical. But how? and Why? \n\nLets explain surface tension first- \nIn an air-water interface, the molecules that are close to the surface are attracted by fewer molecules of the liquid than the ones that are NOT close to the surface. The former thus, has less attractive potential energy than the latter, right?\n\nNow, for any matter (solid or liquid), attractive potential energy results in stability & repulsive energy results in instablity (common sense). \n\nSo, it is energetically unfavourable to have a surface for a liquid (or solid) as it results in loss of attractive potential energy.\n\nNow, for that reason, a bubble wants to have the lowest possible surface area to remain stable. Now, using some high level mathematics, someone found out that a sphere has the lowest possible surface area for a given volume. (it is better than a cube atleast).\n\nHence why we can see that the water bubbles and drops tend to be spherical. Due to the effect of gravity, although the drops appear oval in shape but, in the absense of gravity, all the liguid-air surfaces tend to be spherical.\n\nI hope it helped.\nHave a nice day!
663820
It may be surface tension.
266278
Oh yeah. Shape is everything. A sphere is the perfect shape for holding pressure. But the reason we dont see many spheres holding pressure is that they are also inconvenient in shape, so we have the next best thing - cylinders. LGP tanks, oxy tanks, scuba cylinders etc. Round sides even out the pressure, thats why you dont see square tanks. Also remember that when they test a tank for how well they hold pressure they fill it with water and pressurise the water, if you did this with just air, it will explode when the pressure gets too high. Thats called a hydraulic pressure test and it is marked on all pressure vessels. There is a test pressure and safe working pressure stamped in to all tanks.