Example of Conversions in Thermodynamics

Difference between heat and temperature: Heat is the energy that passes from one body to another, while temperature is the measure of the kinetic energy of each molecule.
Thermal equilibrium: It is the moment in which two or more bodies of different temperatures reach an equilibrium due to the transfer of heat energy from one of them, until they reach an equal temperature.
Absolute thermometric scales
Absolute temperature: It is the measure of the average kinetic energy of each molecule measured in degrees Kelvin.
Celsius: It is the measurement in degrees of temperature based on the melting point (0 ° C) and the boiling point (100 ° C) of water at 1 atmosphere.
Fahrenheit: It is the measure in degrees of temperature that it proposes (32 ° F) for the melting point and (212 ° F) for the boiling point of water at 1 atmosphere.
Kelvin: It is based on the lowest temperature that can be obtained (absolute zero) and corresponds to - 273 ° C = 0 ° K and its scale is Celsius.
Rankine: It is based on the lowest temperature that can be obtained in a body (absolute zero), but in this case the scale will be the same as that of degrees Fahrenheit and corresponds to - 460 ° F = 0 ° R

EXAMPLE OF CONVERSION:

A patient in a hospital has reached the body temperature of 40 ° C, you want to know that temperature in degrees Fahrenheit, Rankine and Kelvin.
First the relationship between degrees centigrade and the other scales is determined.
° K = ° C + 273 = 40 + 273 = 313 ° K
° F = 9/5 (° K -273) + 32 = 9/5 (313 -273) + 32 = 104 ° F
° R = ° F + 460 = 104 + 460 = 564 ° R
Hot: It is the energy that passes from one body to another when it has a different temperature. Heat is cause and temperature is effect. Its units are:
Calorie: Amount of heat needed to raise the temperature 1 ° C of a gram of water.
Kilocalorie: Heat needed to raise the temperature 1 ° C of a kilogram of water.
B.T.U: Amount of heat to raise the temperature 1 ° F of a pound of water.
Joule: Known as the mechanical equivalent of heat and is equal to: 1 cal = 4.18 J
Specific heat capacity: It is the amount of heat that a body supports or can emit.
Specific heat: It is the necessary heat applied to the unit of mass to increase its temperature by 1 ° C.
Latent heat: It is the heat that must be supplied to the kg of a substance at the transformation temperature, to change its state.
Q = cal
m = kg
C_l = kcal / kg
C_l= Q / m

EXAMPLE OF LATENT HEAT PROBLEM:

Calculate the latent heat of a body of mass 2.3 kg that produces a force of 245 N over a distance of 12 m.
First determine the work that is being done.

W = Fd = (245 N) (12 m) = 2490 J
Once the work is obtained in Joules, they are transformed into calories with the following relationship:

1 cal - 4.81 J
x cal - 2490 J

x cal = (1 cal) (2490 J) /4.81 J = 517.64 cal

Finally, the result of heat is substituted into the latent heat equation:

C_l= Q / m = 517.67 cal / 2.3 kg = 225.03 cal / kg

Heat of fusion: It is the amount of heat energy required to melt the unit mass of a solid substance. This same amount of heat must be radiated when the substance solidifies.
Heat of vaporization: It is the amount of energy required to separate the molecules contained in a unit of mass and change the substance from the liquid phase to the vapor phase.