Question 400: Properties of Matter

Question

A cylindrical rod having temperature T
1
and T
2
at its end. The rate of flow of heat Q
1
cal/sec. If all the linear dimension are doubled keeping temperature constant, then rate of flow of heat Q
2
will be

Accepted Answer

Heat flow rate  $${{dQ} \over {dt}} = {{KA\left( {{T_1} - {T_2}} \right)} \over L} = Q$$
When linear dimensions are double.
$${A_1} \propto r_1^2,{L_1} = L$$
$${A_2} \propto 4r_1^2,{L_2} = 2L \Rightarrow {Q_2} = 2{Q_1}$$

Answer

4Q
1

Answer

2Q
1

Answer

$${{{Q_1}} \over 4}$$

Answer

$${{{Q_1}} \over 2}$$

Properties of Matter

A cylindrical rod having temperature T 1 and T 2 at its end. The rate of flow of heat Q 1 cal/sec. If all the linear dimension are doubled keeping temperature constant, then rate of flow of heat Q 2 will be

Choose the correct answer: