Conduction between two materials

In summary, when a metal object and a plastic object are both at 0 degrees, the metal feels colder to the touch because it conducts heat away at a faster rate due to its better conductivity. This means that the warmer material plays a role in how quickly heat is conducted into another material. However, if the metal and plastic are both at 60 degrees, they will not feel the same to the touch as the metal will still conduct heat into the hand at a greater rate. The formula for heat transfer in this scenario is governed by the diffusion equation and the key parameter is the diffusivity. Heat transfer between different materials is more complicated and can be explored further through research and reference texts.
  • #1
sgstudent
739
3
When I have a metal object at 0 degrees and a plastic object at 0 degrees, the metal feels colder as heat is conducted away at a faster rate. The reason for that would be that the metal is a better conductor of heat so when my hand touches it, it can start vibrating more quickly than the plastic.

So does this mean that how fast heat gets conducted into another material depends on the warmer material? For example if the metal and plastic is at 60 degrees, when I touch them they should feel the same? Because now that heat is transferred to the hands, the rate of heat flow into the hand from the hotter object will be the same (since the kinetic energy of the metal and plastic particles is the same so they should have the same rate of heat transfer to the hand). Is this correct?

Thanks :smile:
 
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  • #2
Nope. The metal would feel warmer and conduct heat into your hand at a greater rate.
Not only is the metal able to conduct heat into your hand better, it is also able to conduct heat within itself better too, so it also replaces the heat lost at the point of contact with your hand at a greater rate than the plastic can.
 
  • #3
So does this mean that how fast heat gets conducted into another material depends on the warmer material?

as, posted already, no; It depends on the temperature difference between materials and the conduction rate of the poorer conductor.
 
  • #4
Drakkith said:
Nope. The metal would feel warmer and conduct heat into your hand at a greater rate.
Not only is the metal able to conduct heat into your hand better, it is also able to conduct heat within itself better too, so it also replaces the heat lost at the point of contact with your hand at a greater rate than the plastic can.

Oh that's right! But if I were to touch it for a brief moment then they would feel the same? Or would the touch be too slow? Also what is the formula for this? Thanks
 
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  • #5
sgstudent said:
Oh that's right! But if I were to touch it for a brief moment then they would feel the same? Or would the touch be too slow?

That depends on how brief. If brief enough you wouldn't feel anything. A little longer and the metal would feel hot while the plastic probably wouldn't.

Also what is the formula for this? Thanks

Sorry, I don't know that one.
 
  • #6
Heat transfer is governed by a second order differential equation called the diffusion equation, and the key parameter governing the rate of transfer is the diffusivity. Wikipedia is a good starting point for this
http://en.wikipedia.org/wiki/Heat_equation
Heat transfer across the boundary between different media is a little more complicated. I can refer you to appropriate texts if you are interested.
 

What is conduction?

Conduction is the transfer of heat or electricity between two materials that are in direct contact with each other.

How does conduction occur between two materials?

Conduction occurs when there is a difference in temperature or electrical charge between two materials. Heat or electricity will flow from the material with higher energy to the material with lower energy until both materials reach equilibrium.

What factors affect the rate of conduction?

The rate of conduction is affected by several factors, including the thermal conductivity of the materials, the surface area of contact between the materials, and the temperature difference between the two materials.

How is conduction different from convection and radiation?

Conduction differs from convection and radiation in that it requires direct contact between materials for heat or electricity to transfer. Convection involves the transfer of heat through the movement of fluids, while radiation is the transfer of heat through electromagnetic waves.

How is conduction used in everyday life?

Conduction is used in many everyday applications, such as cooking on a stovetop, using a heating pad, or using a metal spoon to stir a hot beverage. It is also an important process in the functioning of electronic devices and in thermal insulation.

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