- #1

Dx

I said 60C

why is this incorrect?

Dx

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- Thread starter Dx
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- #1

Dx

I said 60C

why is this incorrect?

Dx

- #2

Tom Mattson

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It's not correct because 60^{o} is the *final* (not initial) temperature.

- #3

Dx

I see

dx

dx

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- #4

Dx

Originally posted by Dx

Thanks Tom!

dx

- #5

HallsofIvy

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The problem with asking someone to give you the answer is that they may just give you a WRONG answer!

is not correct. You don't know what the "final" temperature will be because you don't know the temperature of the environment. In order to do this problem, you will have to interpret "initial" temperature as the temperature immediately AFTER mixing.It's not correct because 60 degrees is the final (not initial) temperature.

What makes you think the temperature will be 60 degrees? The only way I see that you can get 60 is to subtract 20 from 80. Do you have any reason for that? If the two temperatures had been 60 and 50 would you say that the mixture will be 10 degrees? Does that even make sense?

It should make sense to you that if you mix two things the final temperature will be BETWEEN the two original ones. In fact you should think about finding the average of the two temperatures.

What is the average of 20 and 80 degrees?

You should also think about how you would "average" the temperatures there were more water at one temperature than the other.

Suppose you had 10 grams of water at 20 degrees and 40 grams of water at 80 degrees. ABOUT what do you think the temperature of the mixture would be? How would you calculate it exactly?

- #6

Dx

Originally posted by HallsofIvy

Once again, DX, be careful of Tom's answers.

The problem with asking someone to give you the answer is that they may just give you a WRONG answer!

is not correct. You don't know what the "final" temperature will be because you don't know the temperature of the environment. In order to do this problem, you will have to interpret "initial" temperature as the temperature immediately AFTER mixing.

What makes you think the temperature will be 60 degrees? The only way I see that you can get 60 is to subtract 20 from 80. Do you have any reason for that? If the two temperatures had been 60 and 50 would you say that the mixture will be 10 degrees? Does that even make sense?

It should make sense to you that if you mix two things the final temperature will be BETWEEN the two original ones. In fact you should think about finding the average of the two temperatures.

What is the average of 20 and 80 degrees?

You should also think about how you would "average" the temperatures there were more water at one temperature than the other.

Suppose you had 10 grams of water at 20 degrees and 40 grams of water at 80 degrees. ABOUT what do you think the temperature of the mixture would be? How would you calculate it exactly?

Let me see. 20 + 80 = 100 / 2 = 50 average. I think i understand better now Ivy. Thanks! Can I add you as a friend, plz? Let me try to work the problem further and if I jave anumore problems ill ask.

Dx

- #7

Tom Mattson

Staff Emeritus

Science Advisor

Gold Member

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- 8

Originally posted by HallsofIvy

You should also think about how you would "average" the temperatures there were more water at one temperature than the other.

Actually, I assumed he did average them and that's how he got 60

- #8

Dx

Just teasing, i am glad to see that everyone has each others back. Thanks HallsOfIvy,

I appreciate your help and toms too.

Dx

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