Why is it that when I spin my cup of hot chocolate round to get a blob of cream towards my mouth, the hot chocolate does not spin round with the cup? The cup spins but the liquid inside doesn't seem to move inside it. Why is this?
2007-01-29 09:23:18 · 6 answers · asked by dnbgrrly 2 in Science & Mathematics ➔ Physics
because the friction coefficient between the liquid and the wall of the cup is so small (near zero), so when u spint he cup, it doesnt take the liquid with it.
u can compare it to cream for example. if you have thick cream, since it is more viscose, it has a higher friction to the wall and bottom of the cup, and it will spin as u spin the cup :)
2007-01-29 09:33:15 · answer #1 · answered by alwayss_ready 3 · 0⤊ 0⤋
The liquid inside the cup has resting inertia. Spinning the cup does not move the liquid because a body at rest (the liquid) tends to stay at rest unless an outside force acts on it. Very little of the force applied to spin the cup gets translated to the liquid inside. So, the cup spins but the hot chocolate doesn't.
2007-01-29 09:33:19 · answer #2 · answered by Doctor J 7 · 0⤊ 1⤋
The choc has inertia - it doesn't have any angular momentum.
You are turning the cup in the hope that this will impart angular momentum to the choc.
It can only do this by friction, first from the wall of the cup to the choc nearest the wall, then from that choc to the choc that's next to that, then then then and so on into the centre. That takes a lot of persistent cup spinning.
That's why spoons work better - they use form drag rather than frictional drag - they push the choc round rather than trying desperately to slither it.
You could invent a mug with inward facing spokes, but it would be harder to clean. Choc would get stuck. Yuk.
2007-01-29 09:31:09 · answer #3 · answered by wild_eep 6 · 2⤊ 1⤋
Prof. Stephen Hawking was asked this but he doesn't drink hot chocolate.
2007-01-29 09:28:13 · answer #4 · answered by Anonymous · 0⤊ 1⤋
If i were to dream up questions like this i would be worried.
2007-01-29 09:28:36 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Its `Centrifugal` force I think.
2007-01-29 12:45:38 · answer #6 · answered by CLIVE C 3 · 0⤊ 0⤋