Question

A thickness of a material is a factor that affects heat conductivity. Does heat flow faster through a thick or a thin piece of the same material?

The surface area of a material is a factor that affects heat conductivity. Does heat flow faster through a large surface area or through a small surface area? Why? (Hint: Think about the number of particles available to bump into one another).


Change in temperature is a factor that affects heat conductivity. Will heat flow faster when there’s a large change in temperature or a small change in temperature?

Answer 1

Answer:

1. Heat flows faster through a thin material.

2. Heat flows through a large surface area.

3. Heat flows faster for a large change in temperature.

Explanation:

Thinking process:

Newton's law of cooling or heat transfer is given by the following equation:

$Q= kA\delta T$

Where Q = Heat change (J)

A = area of hear transfer (m²)

$\fdelta$$\delta T$ = Change in temperature.

However, for a temperature difference across the wall having a thickness "x"and  a constant surface area A, we get,

$Q= k.A\frac{T_{1} - T_{2} }{x}$

Where x = thickness of the material

As we can see, increasing the thickness, x, decreases the heat flux

Increasing the area, A increases the heat flux

A big temperature increase, ΔT results in a large heat transfer.