Question

A steel rod of length 4 m is welded to the end of an aluminum rod of length 3 m (lengths measured at 23 °C). The combination rod is then heated to 198 °C. What is the length of the combination rod at 198 °C? (The linear expansion coefficients for steel and aluminum are 1.3 10-5 °C−1 and 2.2 10-5 °C−1, respectively. Enter your answer to three significant figures.)

I know the equation to be used is, delta length=(linear coefficient of expansion)(length)(delta temperature)

i am confused as to what to use for length on the right side of the equation, and what to subtract from delta length

Answer 1

Hmmm. Do it in two parts, steel expansion, and aluminum expansion, then add the two expansions.

Answer 2

What do i use for delta length?

Answer 3

That is what you are solving for.

deltaLengthAl= coeff*changetemp*lengthorigAl
deltaLengFe= coeff*changetemp*lenghorigFe

Total changelenght= sum of above

Answer 4

it didn't give me the correct answer