A copper rod has a length of 1.3 m and a cross-sectional area of 3.6 10-4 m2. One end of the rod is in contact with boiling water and the other with a mixture of ice and water. What is the mass of ice per second that melts? Assume that no heat is lost through the side surface of the rod.

Respuesta :

To solve the problem it is necessary to apply the concepts related to heat flow,

The heat flux can be defined as

[tex]\frac{dQ}{dt} = H = \frac{kA\Delta T}{d}[/tex]

Where,

k = Thermal conductivity

A = Area of cross-sectional area

d = Length of the rod

[tex]\Delta T=[/tex] Temperature difference between the ends of the rod

[tex]k =388 W/m.\°C[/tex] Thermal conductivity of copper rod

[tex]A = 3.6 *10^{-4} m[/tex] Area of cross section of rod

[tex]\Delta T=100-0=100\°C[/tex] Temperature difference  

[tex]d=1.3m[/tex] length of rod

Replacing then,

[tex]H = \frac{kA\Delta T}{d}[/tex]

[tex]H = \frac{(388)(3.6 *10^{-4})(100)}{1.3}[/tex]

[tex]H=10.7446J[/tex]

From the definition of heat flow we know that this is also equivalent

[tex]H = \dot{m}*L[/tex]

Where,

[tex]\dot{m} =[/tex] Mass per second

[tex]L = 334J/g[/tex] Latent heat of fusion of ice

Re-arrange to find [tex]\dot{m},[/tex]

[tex]H = \dot{m}*L[/tex]

[tex]\dot{m}=\frac{L}{H}[/tex]

[tex]\dot{m}=\frac{334}{10.7446}[/tex]

[tex]\dot{m} = 31.08g/s[/tex]

[tex]\dot{m}= 0.032g/s[/tex]

Therefore the mass of ice per second that melts is 0.032g