Heat conduction through a layers of different materials

[curiosity colour]

Homework Statement

Question C(ii)

Homework Equations

dQ/dt =-kA(dθ/dx)
dQ/dt = (θ₁-θ₂)/ ((l_x/k_xA_x)+ (l_y/k_yA_y))

The Attempt at a Solution

So the first time I tried at this question, I was using the second equation provided above,but when I check the answer, they put the area on the numerator. which left me wonder, how did they make it on top, I've check my textbook but none of it give any clues. If area is on the numerator with θ, I think k should be too isn't it?

 

[mjc123]

If A_x = A_y = A, you can multiply numerator and denominator by A, so A will appear in the numerator and not the denominator. You can do the same with k if k_x = k_y, but that is not the case in this problem.

 

[Chestermiller]

I’ve moved this to the precalculus math forum where they can help you learn algebra.

 

[curiosity colour]

If A_x = A_y = A, you can multiply numerator and denominator by A, so A will appear in the numerator and not the denominator. You can do the same with k if k_x = k_y, but that is not the case in this problem.

I see, thanks for your answer