Test: Basic Concept - 2 - Mechanical Engineering MCQ

Correct Answer :- d

Explanation : A thermodynamic system is a quantity of matter of fixed identity, around which we can draw a boundary The boundaries may be fixed or moveable. Work or heat can be transferred across the system boundary. Everything outside the boundary is the surroundings.

When working with devices such as engines it is often useful to define the system to be an identifiable volume with flow in and out. This is termed a control volume.

A closed system is a special class of system with boundaries that matter cannot cross. Hence the principle of the conservation of mass is automatically satisfied whenever we employ a closed system analysis. This type of system is sometimes termed a control mass.

The concept of continuum loses validity when the mean free path of the molecules approaches the order of magnitude of the dimension of the vessel. So, in highly rarefied gases the concept of continuum loses its validity.

Concept:

Properties

All measurable characteristics of a system are known as properties.

Eg. Pressure, volume, temperature, etc.

There are two types of properties:

Extensive property

• Those properties which depend on mass are known as extensive properties.
• Examples are volume, energy, enthalpy, entropy etc.

Intensive property

• Those properties which don't depend on mass are known as intensive properties.
• Examples are pressure, temperature, density, viscosity.