Wouldn’t it make more sense to have the cup be a consistent width throughout? Or, even make the cup wider at the bottom to make it more stable when sitting on a surface?
In: Engineering
The widening lip helps to prevent spillage/leakage from under/around your mouth, while also giving the container significantly more volume. The mouth of a standard pint glass is somewhere around a foot long. They also allow the containers to be compactly stored by stacking/tesselating them. These three advantages far outweigh any advantage other shapes have.
Slippery cup + wet hand = dropped beverage.
So, cups have this design so that as gravity pulls the drink downward, the flaring taper counteracts that effect keeping it safely in place inside your hand.
If the taper went the other direction, as you squeezed your hand tighter, you could actually force the cup through your closing fist (kind of like squeezing a slippery bar of soap and it popping out of your hand.
Also, it’s WAY easier to store 100 cups if they all fit inside each other, than if they have to be individually placed on the counter. Uniform width, and fat bottomed cups can’t stack inside each other.
Edit: Typo
Cups are made that way so they are easy to release from the molds when they are manufactured. Also, it makes the cups stackable.
It’s easier to stack a cup that’s wider at the top than one that’s the same width the whole way up or one that’s wider at the bottom. It also makes it a little easier to drink, but I don’t think that’s as much of a reason as the stacking since just making it wide enough to drink easily the whole way down would also work.
I don’t actually know but I assume it to make the liquid easier to pour down your mouth without needing to turn your cup upside down to get something and potentially having everything spill because of how sudden it would be.
Also having a wider base and a narrow opening is bad for the environment. [https://www.youtube.com/watch?v=Hyq1uXzV1VE](https://www.youtube.com/watch?v=Hyq1uXzV1VE)
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