Can someone check my answer for a Physics question?

[Azndude51]

Two 0.327 cm metal rods, one made of copper and one made of aluminum, are placed end to end, touching each other. One end is fixed, so that it cannot move. The rods are heated from 0.0 degrees Celsius to 154 degrees Celsius. The coefficient of linear expansion for copper is 16e-6 K^-1 and for aluminum is 22.5e-6 K^-1. How far does the other end of the system of rods move? Answer is in millimeters.

Here's what I did:
I used the equation for thermal expansion: Change in L = (coef. of thermal expansion)(initial L)(change in T)

(3.27mm * 154K)(16e-6 K^-1 + 22.5e-6 K^-1) = .0194mm

I put the answer in and it is incorrect. What am I doing wrong?

 

[Chaotic42]

Edit: NM, I looked at the problem wrong.

 

[gsethi]

I think it will be like this:

Change 154C to kelvin first: 427K

Linear Expansion of Copper rod + Linear Expansion of Al Rod:
Delta L = (3.27mm x 16e-6 K^01)(427 K) + (3.27mm x 22.5e-6 K^01)(427 K)

EDIT: how are the rods placed ?

CCCCAAAA
or
CCCC
AAAA ??

 

[Azndude51]

Originally posted by: gsethi
I think it will be like this:

Change 154C to kelvin first: 427K

Linear Expansion of Copper rod + Linear Expansion of Al Rod:
Delta L = (3.27mm x 16e-6 K^01)(427 K) + (3.27mm x 22.5e-6 K^01)(427 K)

EDIT: how are the rods placed ?

CCCCAAAA
or
CCCC
AAAA ??

Why 427K? Isn't it change in T and not final T?

Also, IDK exactly how they're placed, I copied and pasted the problem and there is no diagram to go with it. I was thinking it is CCCCAAAA

 

[Azndude51]

bump

 

[Paperdoc]

gsethi is wrong, the factor to consider is CHANGE in termperature, not absolute temperature.

What you did is exactly right for the problem as stated. So, go back to the original problem statement and check whether you interpreted it incorrectly. Otherwise, who says your answer is wrong? And what answer was expected? I have certainly encountered textbooks with problems and answers provided in which a few answers were wrong!

 

[Azndude51]

Originally posted by: Paperdoc
gsethi is wrong, the factor to consider is CHANGE in termperature, not absolute temperature.

What you did is exactly right for the problem as stated. So, go back to the original problem statement and check whether you interpreted it incorrectly. Otherwise, who says your answer is wrong? And what answer was expected? I have certainly encountered textbooks with problems and answers provided in which a few answers were wrong!

It is for my online homework, so I do not know what the correct answer is. I inputed it, and it tells me that I am wrong. I have tried different variations, with dif number of sig figs and it's still wrong.

 

[Evadman]

.400

 

[Azndude51]

Originally posted by: Evadman
.400

Can you give me a little more information about how you got that answer? I only have 1 more try before in order to get credit for the problem.

 

[Azndude51]

Okay, my original answer is correct, the problem now shows up as correct, I guess they noticed the error and corrected it today. Thanks for your help, anways.