Let's just say that Dr.H has two glasses of water that are 100mL each. One is 80C and the other is 60C. What will be the stable temperature of the mixture when I pour them both in one container?
Is it:
a) 60C
b) 65C
c) 70C
d) 75C
e) I know that it's a number in between the two but I'm not sure how to calculate it.
2007-09-22 07:55:24 · 6 answers · asked by Dr. H(Relax!) 1 in Science & Mathematics ➔ Physics
You aren't the REAL Dr. H.
I know because he bans all real physicists from reading and making fun of his questions.
I'm sure Dr. H puts some kind of funky solute in his water so that it boils when you mix the glasses or something.
2007-09-22 07:58:31 · answer #1 · answered by Anonymous · 1⤊ 1⤋
Almost everyone missed the right answer. You don't need 8 glasses a day. Guess when the 8 glasses reccomendation came out? After we learned our tap water may be contaminated and that water from a bottle was safe and convenient. Surprise, surprise, who benefits from 8 glasses a day? The truth of the matter is that we, as a species, have done surprisingly well without the 8 glasses a day reccomendation that's become so popular in the last couple decades. Wonder how we did that... couldn't be drinking when you are thirsty, could it? What a terribly odd notion, that. If you are not thirsty and all you had was 3 mountain dews, you're fine. That's apparently all you needed. We're all different, as already said. Tea, coffee, juice, water, "purple drink," soda (even the regular ones with caffeine) all count as water. And I would even agree with Mayor West that a 3% beer counts as water (much more than that and the alcohol's dieuretic effects may outweigh the amount of water you intake from it).
2016-05-21 00:32:19 · answer #2 · answered by ? 3 · 0⤊ 0⤋
In these kind of questions, you assume the final temperature of the mixture to be t.
Let Substance A have mass m1 specific heat capacity C1 and temperature t1 and Substance B have mass m2 specific heat capacity C2 and temperature t2
Let us also assume that t1 > t2.
So A will lose heat and B will gain heat
But
Heat lost = Heat gained
or
m1 * C1 * (t1 - t) = m2 * C2 * (t - t2)
You are given with all the values except one which can be calculated.
But in this case, it is quite easy.
Since the volume of both the glasses is same and the substance is also same (water), therefore the final temperature would be the average of the two i.e. 70C
Since both the substances are water, C1 = C2.
Also V1 = V2 is given.
Multiply both sides with density of water.
So m1 = m2
Put in the equation. You will get t = (t1 + t2) / 2
So you can simply take the average of the two.
Hope this helps.
your_guide123@yahoo.com
2007-09-22 08:02:47 · answer #3 · answered by Prashant 6 · 0⤊ 0⤋
It's the total thermal energy (which is constant) divided by the total mass. So, since the heat capacity of both fluids is the dame (1 cal/gm/degree) and teh masses are the same, it'll be 70 C.
These kinds of problems are a -lot- more fun when you have materials of different thermal capacities and different masses (and maybe throw in a phase change or two ☺)
Doug
2007-09-22 08:03:48 · answer #4 · answered by doug_donaghue 7 · 0⤊ 0⤋
I'd put my money on c) because it is the average of those two temperatures. The volumes are identical so we don't need to worry about proportions.
2007-09-22 08:00:21 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Not enough info, What is the temp of the container that you poured them both into?
2007-09-22 08:00:22 · answer #6 · answered by Mugwump 7 · 0⤊ 0⤋