Quelpr
5 marksHeat Transfer

CAPE Physics Unit 1 · 2008 · Paper 2 · Question 6(a)(ii)

A scientist is investigating the rate of conduction, P, of thermal energy through various thicknesses, x, of a material for supermarket cold room walls. Figure 6 shows results for samples with an area of 0.25 m², for fixed inside and outside temperatures of -5 °C and 30 °C respectively.

Use the graph to find the rate of flow of thermal energy when x = 2.5 cm and when x = 4.5 cm.

This question uses a figure or table from the paper — you'll see it when you practise.

The mark scheme is shown once you've answered.

Practise this question

Other parts of this question

  1. 6(a)(i)Write a formula relating P to the inside and outside temperatures of the material, θ₁ and θ₂, and the thickness, x.[1 mark]
  2. 6(a)(iii)Use the gradient of the graph to find the thermal conductivity of the material.[3 marks]
  3. 6(a)(iv)Sketch the graph which would have been obtained if P were plotted against x instead of 1/x.[2 marks]
  4. 6(b)Estimate the net rate of heat loss from his body after just entering the room.[4 marks]

More practice: the rest of this paper · more Heat Transfer questions · all CAPE Physics Unit 1 past papers