- #1
johns123
- 34
- 0
Homework Statement
A glass mug has mass 125g empty. It contains 180g of
coffee. Both are at 70 C. I add 15g of creme at 5 C.
Find final temperature. Assume creme has specific
heat of 2900 J/kg.C .
Homework Equations
Q = m C (delta)T in joules or Kcalories
m = mass in kg
C is specific heat where C-coffee 1 kcal/kg.C
C-glass .2 kcal/kg.C
C-creme 2900 J/kg.C
delta T is *change* in temperature
The Attempt at a Solution
Attempt at solution: First I don't see a "change"
in temperature. But I'm somehow suppose to apply
the above formula for Q-heat energy. There are 3
Qs .. 2 at 70 C .. and 1 at 5 C. I am somehow
suppose to weight these separate energies, calculate
a change in temperature. Then show the final equilibrium
temperature.
I can only guess that I can do something like
Q-coffee = mC-coffee x 70 to get an absolute ?? energy
Q-glass = mC-glass x 70
Q-creme = mC-creme x 5
and somehow weight the absolute thermal energies to
get delta-T .. and then T ??