why do sodas fizz more when u fill a glass then don't when u top the glass up?

Answer 1

the reason it fizzes is because of the physical shock of hitting the bottom/sides of the glass. When you're just topping it up, the soda is just pouring into the soda which is already there. Soft landing so no fizz.

Answer 2

The walls of the glass have minuscule imperfections on the surface and when the carbon-dioxide gas in the soda scramble and collide while being poured into the glass the gas bubbles explode into more tiny bubbles causing that fizz and foam. Less glass surface exposed equals less foam and fizz.

Science can be so cool ! =)

Answer 3

Usually it is the temperature difference between the glass and the soda this difference will cause the co2 to expand and release from the soda, thus causing the foam. we you top up the glass the soda in the glass is already temperature equalized to the glass and is able to help prevent the sudden release of the co2 when pouring.