Heat flow through oven glass door in 1 hour

[hoyy1kolko]

Homework Statement

The door of an oven has a piece of glass of dimensions 20cm X 30 cm and thickness 0.50cm.when the interior of the oven is at temperature 200°C,determine the quantity of heat that flow through the glass in one hour.(for glass,K=0.80 Wm^-1K^-1)

Homework Equations

Q=tkA(θ2-θ1) /x

The Attempt at a Solution

Q=(3600)(0.80)X(0.2x0.3)(200) / (0.50 x 10^-2)

THe answer given is 6.2MJ.i get 6.9MJ.WHY?please help me to solve this question.

 

[gneill]

What is the temperature of the kitchen?

 

[hoyy1kolko]

the question din given

 

[gneill]

So you assumed zero °C rather than a typical room temperature?