Soap bubbles are formed by dipping one end of a jute or Pepsi straw into soapy water and blowing slowly through the other end. Its size is always round. Floating in the air. We are always used to seeing soap bubbles round. But have we ever wondered why the goal? Why not be square without being round?
This is because of the surface tension of the soap-water. It is a kind of gravitational force that pulls water molecules into the smallest possible size. It has been observed that the surface area of a spherical object is the smallest of all the objects it can hold. The area of a sphere made of that amount of material is less than the area of the outer surface of a pyramid, cube, triangle or irregular angle.
If you blow on the pipe, the soapy water swells. In this case, as soon as it is released from the pipe, it becomes round due to the effect of surface tension. The air inside the bubble pushes outwards and the force of surface tension keeps it evenly pressed.
If the air pressure is high, the bubble will burst, and if it is low, it will shrink. The same thing happens with bubble gum. However, the elastic strength of gum rubber works here instead of surface tension.
Elastic forces like surface tension also try to give the rubber the smallest size all the time. When the bubble gum swells in the air of the mouth, the elastic force of the rubber pushes it inwards. The balance of these two pressures keeps him round like a balloon.