Definition
Thermodynamics
Thermodynamics is the branch of physics and chemistry studying heat and other forms of energy and its transfer between bodies. The flow of energy is of great importance to engineers involved in the design of the power generation and process industries.Thermodynamics provides an understanding of the nature and degree of energy transformations, so that these can be understood and suitably utilized.
Definition
System and boundary
A system is the region of analysis containing matter and energy separated from its surrounding by boundaries. A boundary is a closed surface enclosing a system through which transfer of mass and energy may or may not take place.
Definition
Closed and open systems
Open systems can exchange both matter and energy with an outside system.For example, a hot drink poured into a mug. Closed systems exchange energy but not matter with an outside system.One example is fluid being compressed by a piston in a cylinder.
Definition
Intensive and Extensive properties
An intensive property doesn't change when you take away some of the sample whereas an extensive property changes. An extensive property indicates the size of the system.
Examples:
Intensive-pressure, temperature.
Extensive-mass,volume.
Examples:
Intensive-pressure, temperature.
Extensive-mass,volume.
Definition
State variable
A state variable is a property of a system that depends only on the current, equilibrium state of the system and thus do not depend on the path by which the system arrived at its present state. For example, internal energy, enthalpy, and entropy etc.
Definition
Zeroth law of thermodynamics
The Zeroth Law of Thermodynamics states that two systems in thermal equilibrium with a third system separately are in thermal equilibrium with each other.
Definition
Hot and cold bodies
The Zeroth Law is used to measure the hotness or coldness of a body. All bodies in thermal equilibrium are assigned equal temperature. A hotter body is assigned higher temperature than a colder body. Thus the temperatures of two bodies decide the direction of heat transfer when they are put in contact.
Example
Identify feasibility of a physical scenario using Zeroth Law of Thermodynamics
Example:
Body A is in contact with body B, which is in contact with body C. The temperature of A is more than B which is more than C. What is the correct direction of flow in accordance with the zeroth law of thermodynamics?
Solution:
Body having higher temperature will have higher heat and will transfer heat to low temperature bodies if it comes into contact with them. So, in this heat will flow from A to B to C and finally attain same temperature.
Body A is in contact with body B, which is in contact with body C. The temperature of A is more than B which is more than C. What is the correct direction of flow in accordance with the zeroth law of thermodynamics?
Solution:
Body having higher temperature will have higher heat and will transfer heat to low temperature bodies if it comes into contact with them. So, in this heat will flow from A to B to C and finally attain same temperature.
Definition
Application of Zeroth Law of Thermodynamics
For example, consider two separate cups of boiling water. If we place a thermometer into the first cup, it gets warmed up by the water until it reads 100C. We now say that the thermometer is in thermal equilibrium with the first cup of water. Next, we move the thermometer into the second cup of boiling water, and it continues to read 100C. The thermometer is therefore also in thermal equilibrium with the second cup of water. Using the logic of the zeroth law, we can conclude that the two separate cups of boiling water are in thermal equilibrium with each other.
Definition
Difference between heat and temperature
| S.No. | Heat | Temperature |
| 1 | Heat is a form of energy. | Temperature is a measure of the degree of hot or cold. It is a number that is related to energy, but it is not energy itself. |
| 2 | Heat energy depends upon the speed of the particles, the number of particles and the size or mass and the type of particles in an object. | Temperature does not depend on the size or mass of an object. For example, the temperature of a small cup of water is the same as the temperature of a tub of water, But the tub of water has more heat because it has more water and thus more total thermal energy. |
| 3 | S.I unit of heat is Joule. | S.I unit of Temperature is Kelvin. |
Definition
Clinical Thermometer
Clinical Thermometer :Clinical thermometer is used to measure our body temperature. The range of this thermometer is from 35C to 42C. For other purposes, we use the laboratory thermometers. The range of these thermometers is usually from 10C to 110C.
Definition
Precautions Taken While Reading a Thermometer
- Thermometer should be washed before and after use, preferably with an antiseptic solution.
- Ensure that before use the mercury level is below .
- Handle the thermometer with care. If it hits against some hard object, it can break.
- Dont hold the thermometer by the bulb while reading it.
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