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# If 1.2 x 106J of heat energy is given off in 1 sec from a vessel maintained at a...

### Question

If 1.2 x 106J of heat energy is given off in 1 sec from a vessel maintained at a temperature gradient of 30Km-1, the surface area of the vessel is

A) 1.0 x 102m2

B) 9. 0 x 102m2

C) 1.0 x 103m2

D) 9.0 x 104m2

### Explanation:

Generally in thermal/heat conduction, if 1.2 x 106 J is the heat flow per seconds; 30KM-1 is the temperature gradient of the materials; and 400Wm-1K-1 the thermal conductivity of the material, then we have that:
heat flow per seconds per unit area = thermal conductivity x temp. gradient
i.e = 1.2 x 106Area
= 400 x 30
=> 400 x 30 x Area = 1.2 x 106
∴ Area = 1.2 x 106400 x 30
Area = 100m2 or 1.0 x 102m2

## Dicussion (1)

• Generally in thermal/heat conduction, if 1.2 x 106 J is the heat flow per seconds; 30KM-1 is the temperature gradient of the materials; and 400Wm-1K-1 the thermal conductivity of the material, then we have that:
heat flow per seconds per unit area = thermal conductivity x temp. gradient
i.e = 1.2 x 106Area
= 400 x 30
=> 400 x 30 x Area = 1.2 x 106
∴ Area = 1.2 x 106400 x 30
Area = 100m2 or 1.0 x 102m2