A cylinder made of yellow brass (K = 220 W/m degrees C) supports a hot reservoir

Question

A cylinder made of yellow brass (K = 220 W/m degrees C) supports a hot reservoir at a temperature of 51o Celsius. The cylinder rests on a cold reservoir at a temperature of 5o C, has a radius of 0.70 cm, and is 20.0 cm long. Find the rate of heat flow through the cylinder.

To reduce the heat flow, two shorter cylinders with radii of 0.330 cm and a combined length of 20.00 cm are used. The upper cylinder is made of silver (K = 427 W/m degrees C), length = 3.00 cm). The lower cylinder's composition is unknown. The temperature where the two cylinders are in thermal contact is 48.91 degrees C.

Find the rate of heat flow through the combined cylinders.

Find the thermal conductivity (in W/m degrees C) of the unknown substance.

Explanation / Answer

For the second one, because the combined cylinders are combined series, you can just use the rate of heat flow in the silver to get the heat flow along the whole cylinders, which is (427*pi*0.0033^2*(51-48.91))/0.03=1.02 W, then you can use (k2*(A*(48.91-5)))/(0.2-0.03) to find the K for that unknown cylinder. In this case, the top temperature and the bottom temperature is the same from your first question.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.