One end of a brass bar is maintained at 306 oC, while the other end is kept at a constant, but lower, temperature. The cross-sectional area of the bar is 2.16 × 10-4 m2. Because of insulation, there is negligible heat loss through the sides of the bar. Heat flows through the bar, however, at a rate of 2.23 J/s. What is the temperature of the bar at a point 0.215 m from the hot end?

Respuesta :

Answer:

The temperature of the bar at a point 0.215m from the hot end is 286°C

Explanation:

To solve this problem it is necessary to take into account the concepts related to the rate of heat conducted through objects.

Heat flow rate is the amount of heat that is transferred per unit of time in some material,

The formula is given by

[tex]\frac{\Delta Q}{\Delta t} = kA\frac{\Delta T}{\Delta x}[/tex]

Where,

[tex]\Delta Q =[/tex]  is the net heat transfer

[tex]\Delta t=[/tex] is the necessary time

[tex]\Delta T =[/tex] is the temperature difference between the cold and hot sides

[tex]\Delta x =[/tex] is the thickness of the material that conducts heat

k= is the thermal conductivity

A = Cross-sectional area

In our defined values we have to,

[tex]\frac{\Delta Q}{\Delta t} = 2.23J/s[/tex]

[tex]k_{brass} = 109W/m\°C[/tex]

[tex]A= 2.16*10^{-4}m^2[/tex]

[tex]x= 0.215m[/tex]

[tex]\Delta T =(306\°C-T_c)[/tex]

Replacing the values at the equation,

[tex]2.23 = (109)(2.16*10^{-4})\frac{(306-T_c)}{0.215}[/tex]

[tex]\frac{(2.23)(0.215)}{(109)(2.16*10^{-4})}=(306-T_c)[/tex]

[tex]T_c = \frac{(2.23)(0.215)}{(109)(2.16*10^{-4})}-306[/tex]

[tex]T_c = 286\°C[/tex]

Therefore the temperature of the bar at a point 0.215m from the hot end is 286°C