Help rearranging a formula to solve for different variables

  • Thread starter Thread starter Noah159
  • Start date Start date
  • Tags Tags
    Formula Variables
Click For Summary

Homework Help Overview

The discussion revolves around rearranging the formula Q=mc(T2-T1) to solve for the variables T1 and T2. Participants are exploring how to manipulate the equation to isolate these variables correctly.

Discussion Character

  • Mathematical reasoning, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss various attempts to rearrange the formula, questioning the validity of their steps and the application of algebraic principles. Some express confusion over moving terms and the implications of division and multiplication in the context of the formula.

Discussion Status

The discussion is active, with participants providing feedback on each other's attempts. There is a focus on clarifying misunderstandings about algebraic manipulation, and some guidance has been offered regarding the correct approach to isolating variables.

Contextual Notes

Some participants mention specific algebraic tricks and rules, while others express uncertainty about their application in this context. The original poster's initial equations have been questioned for accuracy, leading to further exploration of the correct rearrangements.

Noah159
Messages
12
Reaction score
0

Homework Statement

[/B]
I just got this formula from class : Q=mc(T2-T1) and got task to make 2 more formulas from this one

Homework Equations


How do I make these formulas : T1=? and T2=?

The Attempt at a Solution


T2=Q:mc-T1
T1=-T1
T1=Q:mc+T2
Thanks for help
 
Physics news on Phys.org
Noah159 said:

Homework Statement

[/B]
I just got this formula from class : Q=mc(T2-T1) and got task to make 2 more formulas from this one

Homework Equations


How do I make these formulas : T1=? and T2=?

The Attempt at a Solution


T2=Q:mc-T1
T1=-T1
T1=Q:mc+T2
Thanks for help
Welcome to the PF.

The equations look okay (see kuruman's post below) except for the bolded part. What do you mean by that equation?
 
Last edited:
Note that I changed the thread title to: "Help rearranging a formula to solve for different variables".

I think this will make it a bit more clear what the thread is about.
 
  • Like
Likes   Reactions: berkeman
Noah159 said:
T2=Q:mc-T1
This equation is also problematic. Starting with your equation Q=mc(T2-T1), it looks like you first divided both sides by mc. That is good. What expression did you get? And once you got that expression, what did you do to it to get T2=Q:mc-T1 ?
 
I got Delta T=Q:mc

Delta T=T2-T1 so formula is T2-T1=Q:mc and I just used simple math trick that if you change sides, it just changes from + to - and - to + e.g x=+4 meaning x-4=0

So from T2-T1=Q:mc formula I got these two:
T1=Q:mc-T2
T2=Q:mc+T1
 
You got the equation for T2 correct this time, but the equation for T1 is incorrect. Starting with T2-T1=Q:mc what do you get, using your simple math trick, when you move T1 to the left side and Q:mc to the right side?
 
T2-T1=Q:mc
T2=Q:mc+T1
T2:Q*mc=T1
T1=T2:Q*mc
Did I get it right this time?
 
Sorry, no.

T2=Q:mc+T1 is correct. You want to have Q:mc on the other side. What does your simple math trick say you should do to achieve this goal? You said it yourself
Noah159 said:
it just changes from + to - and - to +
So ...
 
T2-T1=Q:mc

I can't just move Q:mc freely becouse of division between Q and mc and because of multiplication between m and c.
E.g ρ=m:V
Makes m=ρV
So I can't use my math trick
Sorry if I got your question wrong
 
  • #10
Noah159 said:
I can't just move Q:mc freely becouse of division between Q and mc and because of multiplication between m and c.
Yes you can. Here is how and why. Let w = Q:mc. Then your equation becomes T2-T1 = w. Now move things around to get T1 alone on one side. Finally, replace w with what it is the same as, namely Q:mc. This is how algebra works!
 
  • #11
+T2-T1=+w
+T2=+T1+w
+T2-w=+T1
T2-Q:mc=T1
I hope i got it right this time, did I?
 
  • #12
You did, and I hope you learned something from this experience. :smile:
 
  • #13
Thanks for your help. I definitely learned a lot.
 

Similar threads

Replies
2
Views
971
  • · Replies 10 ·
Replies
10
Views
2K
Replies
8
Views
2K
  • · Replies 14 ·
Replies
14
Views
2K
Replies
11
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 34 ·
2
Replies
34
Views
3K