Question

thermal energy

Answer 1

estimate the thermal energy lost by a cup (250 grams) of a coffee while cooling from 200 degree F to room temperature 72 degree F

Answer 2

@wio can you help me out with formula up here

Answer 3

Isn't it some equation with specific heat and such?

Answer 4

ya but there are two equations, i m confused which one to use

Answer 5

Show me the equations.

Answer 6

\[K_{avg} (per molecule) = \frac{ 3 }{ 2 } k _{B} T\] or \[\frac{ 3 }{ 2 } N k_{B} T\]

Answer 7

And \(k_B\) is specific heat?

Answer 8

it is Boltzmann constant

Answer 9

Well, \(N\) and \(k_B\) don't change so: \[
E_2-E_1=\Delta E=\frac 32Nk_BT_2 - \frac 32Nk_BT_2 =\frac 32Nk_B( T_2-T_1)=\frac 32Nk_B\Delta T
\]

Answer 10

So you need to find \(\Delta T\) and \(N\)

Answer 11

But I'm not even sure how you'd find \(N\) since I don't know particles per gram for coffee.

Answer 12

ohk so i think forst formula

Answer 13

Unless you assume it is just water.

Answer 14

it is cofee

Answer 15

most likely they just calculate the coffe as if it was water

Answer 16

oh do you have any idea about that N thing up there

Answer 17

concentrations of coffee vary. if they don't give additional detail, there is not one solution

Answer 18

ohk ty