for example, when i buy a latte or a hot chocolate it seems to get colder waaay quicker than say a coffee just made with hot water like an americano?
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is it just me or does milk get colder quicker than water?
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Posted 3 months ago #
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higher albedo value?
thicker?
more froth?Posted 3 months ago # -
higher albedo value?
Albedo as I understand it should have no effect here.
Posted 3 months ago # -
Starting temperature's different?
Posted 3 months ago # -
It's 'cause they keep the milk in the fridge.
Posted 3 months ago # -
Hot water will be drawn closer to boiling, milk will be heated to around 65C
Posted 3 months ago # -
Have you measured the temperature? Perhaps it's just that milky drinks taste colder?
Posted 3 months ago # -
Isn't the specific heat capacity of milk and air lower than that of water? Therefore will not require as much energy loss for a given temp drop
Posted 3 months ago # -
specific heat capacity of milk is 3.93 kj/kg.k water is 4.2, so it milk heats and cools faster than water.. (if the numbers for milk are correct)
sources
eng tool box
kids physics page
crazy russians pdfedit rhys got there before me...
Also wikepedia on specific heatPosted 3 months ago # -
toys that won't make a noticeable difference.
Froth insulates that's it.
Posted 3 months ago # -
milk heats and cools faster than water
Doesn't it have to lose more heat and therefore take longer ?
I reckon as c-al says, froth insulates. Plus water evaporates easier than milk and therefore loses heat quicker, so contrary to the OP's observations, milk should take longer.
Posted 3 months ago # -
And an Americano will start at a way higher temperature.
Posted 3 months ago # -
Not really relevant but interesting none the less
The Mpemba effectPosted 3 months ago # -
Al and others, your other cod physics might be right, I dunno, but if it heats faster it cools faster. Its got less energy.
The heat in the system Q is equal to the mass x heat capacity x the temp change or Q=MxCpxDTso if the heat capacity is less, then there is less heat in the system. (the density of milk is just higher than the density of water, water is 1kg/l milk is 1.03kg/l)
Assume its a litre
Water at 85celcius heated from 15 =70 degree change
Q=294 Kj
Milk = 283 KjSo Al you might be right because if we assume the same cooling rate then every 4.042 kj lost is a degree lost for the milk, and 0.97 of a degree for the water.. It seems there is not much in it.
Posted 3 months ago # -
Yes toys but a 7% difference in SHC of say 15% of the drink ~ 1%
Oops wrote that out before fully reading your post. Looks like my cod physics agrees with your non-cod physics.
It just seems obvious that the insulating effect of the foam has to trump any SHC stuff, milk being ~95% water.
Posted 3 months ago # -
tbh its much harder to get a reasonable estimate by hand of the actual rate of heating and cooling, so I just went for the easy numbers...
Posted 3 months ago #
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