If you take a glass of water and turn it upside down most of the water dumps out immediately, but not all of it. Why is that?

Question

Why is it that a small percentage of the water is able to defy gravity and cling to the inside of the glass? Also if you hold it upside down long enough more will eventually come out but it feels like it takes forever.

In: Physics

Answer 1

Things tend to stick to each other. Water will stick to water and will also stick to the glass. Gravity will make majority of the water fall out of the glass, but the last couple drops have more “stickiness” to the glass and will take more time to leave. The part that stays even if you hold it upside down has enough “stickiness” that gravity is not enough to make it fall out.