Heat flow through aluminium rod

In summary, the problem involves calculating the thermal conductivity of an Aluminium rod with a diameter of 40mm and a length of 750mm, with a temperature difference of 100C between its ends. Using the equation k * A * ΔT / L, the correct answer is 39.4 Js-1, with the cross sectional area calculated to be approximately 0.097 m.
  • #1
em3
5
0

Homework Statement


An Aluminium rod has a diameter of 40mm. and is 750mm long. If the temperature difference between the ends of the rod is 100C .

Take the thermal conductivity of Aluminium to be 235 Wm-1K-1

Homework Equations


k * A * ΔT / L

The Attempt at a Solution


235 * 0.097 m * 100 / 0.75

The answer is supposed to be 39.4 Js-1 but I can't get it right? So I don't know if I'm doing something wrong, and I've tried so many times. I don't know what I'm doing wrong.
Thanks
 
Last edited:
Physics news on Phys.org
  • #2
Hi em3,

Welcome to Physics Forums!

em3 said:
235 * 0.095 m * 100 / 0.75
How did you arrive at 0.095 m for the cross sectional area?
 
  • #3
40mm. and is 750mm into m, 0.04m and 0.75m. Then did A=2πrL+2πr2

2 * ∏ * 0.02 * 0.75 + 2∏0.022≈ 0.097
Sorry, made a typo in first post
 
  • #4
em3 said:
40mm. and is 750mm into m, 0.04m and 0.75m. Then did A=2πrL+2πr2
You want the cross sectional area, not the total surface area.
 
  • #5
How do I find that? The question only gives me the diameter and length, no inner or outer diameter.
 
  • #6
em3 said:
How do I find that? The question only gives me the diameter and length, no inner or outer diameter.
Assume that a rod is a solid cylinder.
 
  • #7
Oh ok thanks, I got it. Thanks a lot!
 

Related to Heat flow through aluminium rod

1. How does heat flow through an aluminium rod?

The flow of heat through an aluminium rod is a process known as conduction. This means that heat energy is transferred from one molecule to another in a solid material without the actual movement of the molecules themselves. In other words, the heat energy is passed from atom to atom in a chain reaction, resulting in a transfer of heat along the length of the rod.

2. What factors affect the rate of heat flow through an aluminium rod?

The rate of heat flow through an aluminium rod is affected by several factors, including the temperature difference between the two ends of the rod, the length and cross-sectional area of the rod, and the thermal conductivity of the material. A larger temperature difference, shorter length, and larger cross-sectional area will result in a faster rate of heat flow, while a lower thermal conductivity will slow down the rate of heat flow.

3. How is heat flow through an aluminium rod measured?

The rate of heat flow through an aluminium rod can be measured using a device called a thermocouple. This device consists of two different metal wires joined at one end and connected to a voltmeter. When one end of the thermocouple is heated, a voltage difference is produced, which can be used to calculate the rate of heat flow through the rod.

4. Does the surface of an aluminium rod affect heat flow?

Yes, the surface of an aluminium rod can affect heat flow. A rough or uneven surface can create air pockets or gaps, which can hinder the transfer of heat through conduction. A smooth and clean surface allows for better contact between the molecules of the rod, resulting in a more efficient flow of heat.

5. How does the thickness of an aluminium rod impact heat flow?

The thickness of an aluminium rod can impact heat flow by affecting the rate of heat transfer. Thicker rods have a larger cross-sectional area, which allows for more heat to be transferred at a faster rate. However, thicker rods may also have a lower thermal conductivity, which can slow down the rate of heat flow. Therefore, the thickness of an aluminium rod must be considered in relation to other factors, such as temperature difference and length, to determine its impact on heat flow.

Similar threads

Spec'ing the power of heater for an atypical heat exchanger problem
    • Engineering and Comp Sci Homework Help
Replies
22
Views
2K
Electric heat generation from parallel rods carrying current in an oil bath
    • Introductory Physics Homework Help
Replies
11
Views
763
Steady state heat flow: radiation and conduction
    • Introductory Physics Homework Help
Replies
5
Views
2K
Power Radiated From a Copper Cube
    • Introductory Physics Homework Help
Replies
3
Views
102
Diffusion of energy by heat flow
    • Introductory Physics Homework Help
Replies
1
Views
1K
Heat gained and lost by aluminium and water in thermal equilibrium
    • Introductory Physics Homework Help
Replies
1
Views
2K
Two rods are connected one silver and the other gold.
    • Introductory Physics Homework Help
Replies
3
Views
7K
Heat Flow Through Rock Layers Problem
    • Introductory Physics Homework Help
Replies
6
Views
1K
How calculate the Heat flux requiered to evaporate sub cool water
    • Introductory Physics Homework Help
Replies
1
Views
1K
Heat and increasing a rod's length
    • Introductory Physics Homework Help
Replies
7
Views
1K

Hot Threads

Recent Insights

Back
Top