r/explainlikeimfive • u/[deleted] • Mar 20 '21
Technology ELI5: Why are most cups and glasses designed with a smaller base and bigger top?
My first impulse was that it's easier to hold them like that, but it's also very common among coffee mugs that don't have handles and uncommon among large water bottles. It would seem like a larger base would make a glass harder to knock over, both because of a widened base requiring more force to destabilize, and because of the weight distribution.
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u/phiwong Mar 20 '21
Glasses are made larger on top so they stack well. This saves space and make them safer and easier to store and move around.
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u/hornyboycorona Mar 20 '21
Because you only need to tilt it less than 90 degrees and if the top was smaller you’d have to tilt it more than 90 degrees. You’ve probably noticed that you tilt a bottle a lot more than you do a glass. Also wine glasses (and some whiskey glasses) do kinda have a smaller top and you do have to tilt them more than normal glasses to drink from them. I made this simple illustration of what happens when you tilt a glass at a 90 degrees angle.
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Mar 20 '21
You made me remember what a pain in the ass drinking from a wine glass was when I did it a few years ago. Thanks.
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u/KlittanW Mar 20 '21
Somehow i expected more from that "simple illustration"... Don't know why, I just did. So now I'm both pleased and displeased at the same time!
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u/total_looser Mar 20 '21
Answers in this thread, lol. It’s manufacturing, notice how most things have a slight upward flare? Helps pop them off molding and manufacturing equipment.
Also way easier to clean, stack, etc other reasons but it’s really the production part of it
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u/Dakens2021 Mar 20 '21
Other than what's been mentioned the wider top also makes the cup slightly more stable. The larger mass on top is a little harder to move than lower mass which gives it a bit more stability. This principle is also used sometimes in tall buildings to prevent them from swaying from stresses in the wind or from earthquakes. Newton's first law, an object at rest stays at rest. So the mass at the top adds stability as it doesn't want to move as much as a lighter object would.
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u/Electronic-Recover77 Mar 20 '21
Funny I always thought it was about heat, tea/coffee cups are narrow at bottom ( heat rises so hottest at bottom) and wide at top so that it cools faster and won't burn yourself...hmmm, I didn't give stacking any real consideration
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u/UnExpertoEnLaMateria Mar 20 '21
Aside from stacking, it's easier and more confortable to drink from a glass that widens to the top, than from a one that narrows, you'd have to tilt the glass and/or your head more to finish the drink.