Drinking straws are used everyday to drink fluids which are stored in containers like cans. A suck and drink process is easy, but in the merely simple process it is comprised of the usage of atmospheric pressure. Atmospheric pressure is the pressure around us created by the surrounding layer of thick air situated above us.

For instance when one is sucking fluid with the use of straw in a can drink, it creates a region of low pressure inside the straw due to the pressure has been “absorbed” to the mouth. When the pressure of our surrounding (atmospheric pressure) is higher than the pressure inside the straw, it will pushes the fluid towards the inside of the straw, by this the fluid will eventually reaches the mouth of the person. On the other hand if you try to blow the straw, the pressure inside the straw will increase and hence when the inside pressure is higher than our surrounding pressure ( atmospheric pressure) the air inside the straw will be forced to gush out and effervescence will occur .

One can try this at home, simply take a drinking straw and try it with a cup filled with water.