Here is a Theoretical Question I have been pondering

  • #1

Main Question or Discussion Point

Here it goes:

You purchase a cup of coffee at Dunkin Donuts. The coffee is about 90deg. in a styrofoam insulated cup. The main question is: Should you mix your cream, which is about 5deg cels, in the coffee at dunkin donuts or wait til you get home? The temperature outside is about 25deg. Home is about 5-10min away by car. It's not a trick question. Ok it should be that you mix the cream before, but why?
 

Answers and Replies

  • #2
mgb_phys
Science Advisor
Homework Helper
7,774
12
Assuming the intention is to keep the coffee as hot as possible - milk later.
The cold milk will rise in temperature on the way home.
The rate of cooling of the coffee is proportional to temperature so cooler (milky) coffee would cool more slowly but at any point in the cooling curve it will be cooler if the milk is added.
 
  • #3
LURCH
Science Advisor
2,549
118
Also, the rate of heat loss by the coffee is slower not only due to the insulated cup, but the greater volume of the fluid, which makes a greater ratio of mass/surface area. The temperature change in the creamer will be more rapid because it is a smaller body.

But for me, the goal is to get the coffee cooled down enough to begin drinking sooner without burning my mouth, so I add and mix immediately.
 
  • #4
Ranger Mike
Science Advisor
Gold Member
2,118
192
watching Rachel Ray..is it not better to add oneingredient to another in as hot a situation as possible..aids in blending?
i know if you add that dry coffee creamer to a luke warm cup of java..it clumps up..right?
 
  • #5
129
0
watching Rachel Ray..is it not better to add oneingredient to another in as hot a situation as possible..aids in blending?
i know if you add that dry coffee creamer to a luke warm cup of java..it clumps up..right?
Based on my experience, that's true.
 

Related Threads for: Here is a Theoretical Question I have been pondering

Replies
1
Views
1K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
9
Views
2K
Replies
4
Views
2K
Replies
2
Views
1K
Top