Fundamentals of Physics: The Transfer of Heat
Temperature Scales
Ex: At what temperature will the reading on the Fahrenheit scale be numerically equal to that on the Celsius scale?
The relationship between the two scales is given by TF = (9/5)TC + 32.0. We want the temperature when TF = TC, so we make that substitution. Rearranging gives
Heat and Temperature Change: Specific Heat Capacity
Q = mc T 4186 J = 1 kcal
Ex: If 15 kcal of heat are added to 5.0 kg of silver, by how much will its temperature rise?
Ex: An aluminum cup having a mass of 250.0 g is filled with 50.0 g of water. The initial temperature of the cup and water is 25.0 °C. A 75.0-g piece of iron initially at 350.0 °C is dropped into the water. What is the final equilibrium temperature of the system assuming that no heat is lost to the outside environment?
Heat and Phase Change: Latent Heat
The Transfer of Heat
The heat conducted through a bar is
The Stefan - Boltzmann law gives the radiant energy emitted or absorbed by an object:
Radiation
Ex: The sun shines directly on one side of a flat black panel on a spacecraft which has an area of 5.0 m2 and an emissivity of e = 0.95. The spacecraft is located 1.5 1011 m from the sun. How much power does the panel absorb from the sun if the sun is considered to be an ideal blackbody with a temperature of 5700 K? Assuming that the panel can only lose energy through radiation, what is the equilibrium temperature of the panel? A: The total power emitted by the sun is given by equation 13.2 with , the surface temperature of the sun. The radius of the sun is .
This energy spreads out over the surface of a sphere of radius, r, so that the amount reaching the panel is : The panel is in equilibrium if its temperature, Tp, remains constant. This means that the panel is losing as much power as it is gaining. It gains energy only through the one sunlit side, but it can radiate energy from both sides.
Thermodynamics
The first law of thermodynamics is
Ex: At what temperature will the reading on the Fahrenheit scale be numerically equal to that on the Celsius scale?
The relationship between the two scales is given by TF = (9/5)TC + 32.0. We want the temperature when TF = TC, so we make that substitution. Rearranging gives
Heat and Temperature Change: Specific Heat Capacity
Q = mc T 4186 J = 1 kcal
Ex: If 15 kcal of heat are added to 5.0 kg of silver, by how much will its temperature rise?
Ex: An aluminum cup having a mass of 250.0 g is filled with 50.0 g of water. The initial temperature of the cup and water is 25.0 °C. A 75.0-g piece of iron initially at 350.0 °C is dropped into the water. What is the final equilibrium temperature of the system assuming that no heat is lost to the outside environment?
Heat and Phase Change: Latent Heat
The Transfer of Heat
The heat conducted through a bar is
The Stefan - Boltzmann law gives the radiant energy emitted or absorbed by an object:
Radiation
Ex: The sun shines directly on one side of a flat black panel on a spacecraft which has an area of 5.0 m2 and an emissivity of e = 0.95. The spacecraft is located 1.5 1011 m from the sun. How much power does the panel absorb from the sun if the sun is considered to be an ideal blackbody with a temperature of 5700 K? Assuming that the panel can only lose energy through radiation, what is the equilibrium temperature of the panel? A: The total power emitted by the sun is given by equation 13.2 with , the surface temperature of the sun. The radius of the sun is .
This energy spreads out over the surface of a sphere of radius, r, so that the amount reaching the panel is : The panel is in equilibrium if its temperature, Tp, remains constant. This means that the panel is losing as much power as it is gaining. It gains energy only through the one sunlit side, but it can radiate energy from both sides.
Thermodynamics
The first law of thermodynamics is