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Standard VI

Mathematics

Area of Rectangle

One face of a...

Question

One face of an aluminium cube of edge 2 metre is maintained at $100^{\circ}$ C and the other end is maintained at $0^{\circ}$ C. All other surfaces are covered by nonconducting walls. Find the amount of heat flowing through the cube in 5 seconds. (thermal conductivity of aluminium is 209 W/m $^{\circ}$ C)

208 K J

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209 K J

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210

K J

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220

K J

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Solution

The correct option is B $209 K J$
Heat will flow from the end at $100^{\circ}$ C to the end at $0^{\circ}$ C.
Area of cross-section perpendicular to direction of heat flow,
$A = 4 m^{2}$
then $\frac{Q}{t} = K A \frac{(T_{H} - T_{c})}{L}$
$Q = \frac{(209 W / m^{\circ} C) (4 m^{2}) (100^{\circ} C - 0^{\circ}) (5 s e c)}{2 m} = 209 K J$

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One face of an aluminium cube of edge 2 metre is maintained at 100∘C and the other end is maintained at 0∘C. All other surfaces are covered by nonconducting walls. Find the amount of heat flowing through the cube in 5 seconds. (thermal conductivity of aluminium is 209 W/m ∘C)

The correct option is B 209KJHeat will flow from the end at 100∘ C to the end at 0∘ C.Area of cross-section perpendicular to direction of heat flow,A=4m2then Qt=KA(TH−Tc)LQ=(209W/m∘C)(4m2)(100∘C−0∘)(5sec)2m=209KJ