Test: Basic Concept - 1 - Mechanical Engineering MCQ

Thermodynamic cycle can be defined as a series of state changes such that the final and initial state is identical.

In thermodynamics, a system is any part of the universe which is under observation  and the rest of the universe, except the system, are called its surroundings.

So, universe = system + surroundings.

The properties which are mass independent are intensive properties and those which are mass dependent are extensive properties.
Volume depends upon the amount of matter present in the system. Hence, it is an extensive property.

Since heat transfer is the path function hence it is not the property of the system.

Explanation:

- Enthalpy is defined as the heat content of a system at constant pressure. It is represented by the symbol H.

- The unit of enthalpy is derived from the units of energy, which are Joules (J) in the International System of Units (SI).

- The fundamental unit of energy is Joule, which is represented as ML²T^-2.

- Since enthalpy is a form of energy, the fundamental unit of enthalpy is also ML²T^-2.

Open system: Both mass and energy transfer takes place
Closed system: No mass transfer, energy transfer may takes place
Isolated system: Neither energy nor mass transfer takes place.

The value of an extensive property is influenced by various factors:

• Mass or size of the system: The larger the mass, the greater the extensive property.

• Interactions with surroundings: How the system interacts with its environment can affect its extensive properties.

• Path taken between states: The specific process by which the system changes states can impact its extensive properties.

• Nature of boundaries: The type of boundaries, whether rigid or flexible, plays a role in determining extensive properties.

A diathermic wall is a wall that allows the transfer of heat (thermal interaction) through it. The term diathermic comes from Greek, where "dia" means "through" and "therm" means "heat." Therefore, a diathermic wall is one that permits thermal interaction, meaning it allows heat to pass through it.

• Option A (prevents thermal interaction) refers to an adiabatic wall, which prevents heat transfer.
• Options C and D (encourages and discourages thermal interaction) are not standard terms in this context.

Thus, the correct answer is B: permits thermal interaction.

Intensive properties are characteristics of a substance that do not depend on the amount of material present. Here are the properties listed and their classifications:

• Kinetic energy: This is an extensive property because it depends on the mass of the substance.
• Specific enthalpy: This is an intensive property as it measures energy per unit mass, making it independent of the total mass.
• Pressure: This is also an intensive property because it is defined as force per unit area, regardless of the quantity of substance present.
• Entropy: This is another intensive property as it is a measure of disorder per unit of energy, independent of the total system size.

In summary, the intensive properties from the list are:

• Specific enthalpy
• Pressure
• Entropy

A system said to be in thermodynamic equilibrium with surrounding if:

It is in thermal, chemical as well as mechanical equilibrium with the surrounding.

And when system is in thermodynamic equilibrium there won't be any spontaneous change.

Correct option is d) 592 m/s

For reversible process, by first law

For steady flow reversible process,

Since the kinetic energy of the molecules won’t change in vacuum, ⇒ temperature remains constant.