Setting up a simultaneous I think

K

KevinE

New member
Joined
Dec 3, 2014
Messages
34
Using different conditions can help set up and solve equations with more than one unknown.

The resistance R ohms of copper wire at t degrees Celsius is given by R = R0 (1+at)

Given R = 25 omhms at 30oC (degrees Celsis)
R= 32 omhms at 100oC

Calculate using algebra the values of R0​ and a
 
I'm thinking it's some type of simultaneous equation but I can't think how to set it up
 
KevinE said:
Cancel that I think I might have it

Ro = 22

a = 0.0045
Click to expand...

For t = 30 degrees C we have
25 = R0 (1+a 30)
For t = 100 degrees C we have
32 = R0 (1+a 100)

I would divide the 32 equation by the 25 equation and then multiple through by (1 + 30 a) to get an equation for a. Solving that I get a = 0.004545. Having found a I would use one of the equations to find R0 and get R0 = 22.

Thanks for checking my work:grin:
 
A quick English lesson. "Simultaneous" is not a noun so you cannot talk about "a simultaneous". Further, in order to have simultaneous equations, there must be at least two equations so You can't talk about "a simultaneous equation" (singular).
 
Are we having fun folks?

Thanks for English lessons... there was me thinking this was a Math forum...

:0 thanks guys you're great. A thousand blessings upon ye all.
 
Yeh I was thinking that. My English is usually pretty good. Who is he talking to then?

You couldn't check this again someone please? Not that it matters my assignment has gone in.

I set it up as a simultaneous equation.
Two sets of data two unknown variables.

So the equation was

R = Ro (1+at)
25 = Ro (1+a 30)
32 = Ro (1+a 100)

times the first equation by 10
times the second equation by 3

=
250 = 10Ro (1+ 300a)
96 = 3Ro (1 + 300a)

154 = 7Ro

154 / 7 = 22
 
KevinE said:
But I'm just thinking I forgot to multiply the dang 1s
Click to expand...

Looking at both posts, your notation is a little off but you got the right answer: Instead of
250 = 10Ro (1+ 300a)
96 = 3Ro (1 + 300a)
you should have
250 = Ro (10+ 300a)
96 = Ro (3 + 300a)
but that is what you did so it worked out o.k.
 
You must log in or register to reply here.
Top