Heat flow problem (copper pipe)

AI Thread Summary
The discussion revolves around calculating heat flow through a copper bar with specified dimensions and temperature difference. The user initially converted the cross-sectional area incorrectly, which impacted the calculations. The correct conversion of 4.40 cm² to m² is crucial for accurate results. The user also attempted to calculate thermal resistance and current but received an incorrect final value. A fellow participant pointed out the area conversion mistake, highlighting its significance in the overall calculation.
BMcC
Messages
32
Reaction score
0

Homework Statement



A copper bar with a cross sectional area of 4.40 cm2 and a length of 0.62 m has one end at 1 °C and the other end at 97 °C. Find the heat flow through the bar if the thermal conductivity of copper is 385 W/(m·K)

Homework Equations



R = (λ*L)/A

I = ΔT / R

k = 1/λ

R = resistance
λ = thermal resistivity
L = length of pipe
A = cross sectional area

I = thermal current
ΔT = change in temperature

k = thermal conductivity

3. My attempt

So first I converted the area 4.40 cm2 into 0.044 m2.

Then I converted the thermal conductivity given in the problem to thermal resistivity

k = 1/λ
λ = 1/k = 1/385 W/(m·K) = 0.00259 mK/W

Using this value, the area, and the length from the problem, I used R = (λ*L)/A

R = (0.00259 mK/W)(0.62 m) / 0.044 m2
R = 0.0366 K/W

Now I plugged this R into the thermal current formula I = ΔT/R, where ΔT = 97 °C - 1 °C = 96 °C

The ΔT is measured in Kelvin, but is still a difference of 96 units.

I = 96K / 0.0366 K/W = 2622.95 W = 2622.95 J/s

This is incorrect apparently. Does anybody know where I might have went wrong?

Thanks!
 
Physics news on Phys.org
Hello, BMcC. I haven't checked all of your numbers, but I did notice that you made a common mistake in converting 4.40 cm2 to m2.
 
  • Like
Likes 1 person
Ah wow how silly of me. That changes everything. Thanks TSny!
 
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Back
Top