Finding the coefficients of a Resistance vs. Temp curve

AI Thread Summary
To find the coefficients Ro, a, and b for a Resistance vs. Temperature curve, the problem requires measurements at the ice, steam, and sulfur points. The initial calculation shows Ro equals 7 ohms at 0°C, leading to a system of equations for the other two temperatures. The challenge arises because the coefficients for a and b are not easily cancelable, complicating the solution process. After some confusion, the user resolves the issue, noting that their linear algebra course did not cover such scenarios. The discussion highlights the differences in problem-solving approaches between mathematicians and physicists.
guyvsdcsniper
Messages
264
Reaction score
37
Homework Statement
Find Ro, a, and b.
Relevant Equations
R(T) = Ro (1 + aT + bT2 )
I am asked to find Ro, a, and b. Th problem states the values are determined by the measurements at the normal ice, steam and sulfur points. So I approached the problem by plugging the the temperature problems. For 0°C, Ro reduces to 7 ohms. Then for the other two non zero temperatures, it looks like I am left with a system of equations.

I am a bit stumbled because the values associated for a and b of both equations arent factors of each other, so canceling out seems a bit trickier. I don't really recall running across a problem like this before.

Am I approaching this problem correctly? If so what is a way to solve for a and b?
img_b9c76850568e-1-jpeg.jpg
 
Physics news on Phys.org
You have three temperatures which means that you can write three equations, one at each temperature, and three unknowns. The first equation gives you (as you have already found) R0 = 7 Ω. Use that value in the other two equations which form a system of 2 equations and 2 unknowns a and b. Can you solve that?
 
kuruman said:
You have three temperatures which means that you can write three equations, one at each temperature, and three unknowns. The first equation gives you (as you have already found) R0 = 7 Ω. Use that value in the other two equations which form a system of 2 equations and 2 unknowns a and b. Can you solve that?
I figured it out. I actually just finished a linear algebra course and they never gave us a problem like that where the coefficients weren't perfect factors of each other.

Very noob post. Sorry lol
 
quittingthecult said:
I figured it out. I actually just finished a linear algebra course and they never gave us a problem like that where the coefficients weren't perfect factors of each other.
Yes, but don't berate yourself. You were led up the garden path. Mathematicians sometimes have a different view of the world from physicists.
 
  • Informative
Likes guyvsdcsniper
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Trying to understand the logic behind adding vectors with an angle between them'
My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
Back
Top