Question

How are you able to drink juice with straw

Answer 1

When you sit down to a glass of iced tea with a straw in it, you might say that you are sucking the tea up through the straw. In fact, a more accurate description would be to say that the atmospheric pressure is pushing the liquid up the straw.With the straw just sitting in the glass, the pressure on the surface of the tea is the same all over, including on the little bit of surface inside the straw.

When you suck the air out of the straw, you decrease the pressure inside the straw, allowing the higher pressure on the rest of the surface to push the tea up the straw and into your mouth.