A metal bar is used to conduct heat.When the temperature at one end is 110°C and at the other is 25°C,heat is transferred at a rate of 20 J/s.The bar is then stretched uniformly to twice its original length.If again it has ends at 110°C and 25°C,at what rate will heat be transferred between it ends?

Question

Quizplus · Accepted Answer

When the bar is stretched to twice its length, its cross-sectional area is reduced, which increases the thermal resistance. Since thermal resistance is inversely proportional to the cross-sectional area and directly proportional to the length, doubling the length while reducing the area results in a quarter of the original heat transfer rate, which is 5 J/s.

A Metal Bar Is Used to Conduct Heat