Why is it possible for you to suck juice from a glass with a straw?

Question

Why is it possible for you to suck juice from a glass with a straw?

Answer 1

You don't really suck juice from the glass, only from the straw where it flows into the vacuum created when you suck out the air or juice contained in the straw.

Answer 2

Because the atmosphere exerts approximately 14 pounds per square inch of pressure on the liquid in the glass.  When you pucker your mouth and create a partial vacuum, there is a pressure difference between the top of the liquid in the glass and your mouth.

It's not so much that you are 'sucking' the liquid through the straw, as it is the atmosphere is 'pushing' the liquid through the straw into your mouth.

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Answer 3

Because of the differing pressure that you create inside your mouth.  Fluids will move from areas of more pressure to areas of less pressure.

Answer 4

difference of atmospheric pressure between your mouth and the liquid in the glass