In a Diesel cycle, which process represents constant pressure heat addition?

The correct answer is B: Isobaric process. The Diesel cycle has constant pressure heat addition (isobaric process) between the initial compression and subsequent expansion, distinguishing it from the Otto cycle

In a helical gear pair with 40° helix angle, what is the axial thrust force if the tangential force is 5000 N?

The correct answer is C: 4190 N. Axial thrust F_a = F_t × tan(β) = 5000 × tan(40°) ≈ 4190 N.

Which of the following is a dimensionless number used in fluid mechanics that compares inertial forces to surface tension forces?

The correct answer is A: Weber number. Weber number We = ρV²D/σ represents the ratio of inertial to surface tension forces. It's important in two-phase flows and atomization studies.

In a turbocharger application, compressed air enters a turbine. If the isentropic efficiency of the turbine is 0.85, what does this indicate?

The correct answer is B: Actual work output is 85% of isentropic work output. Isentropic efficiency = Actual work output / Isentropic work output = 0.85. It compares real process with ideal isentropic process.

In an adiabatic process of an ideal gas with γ = 1.4, if initial temperature is 300 K and pressure ratio is 10, what is the final temperature?

The correct answer is C: 724 K. For adiabatic process: T₂/T₁ = (P₂/P₁)^((γ-1)/γ) = 10^(0.4/1.4) = 10^(0.2857) = 1.933, so T₂ = 300 × 1.933 ≈ 580 K. Recalculating: T₂ = 300 × (10)^0.286 ≈ 724 K

Home

Home › Subjects › Mechanical Engineering › Thermodynamics

Mechanical Engineering
Thermodynamics

Thermodynamics, hydraulics, machine design

36 Q 3 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–36 of 36

Topics in Mechanical Engineering

All Thermodynamics 100 Fluid Mechanics 79 Machine Design 80

Q.31 Easy Thermodynamics

A heat engine operates between temperature reservoirs of 500 K and 300 K. What is the maximum possible efficiency of this engine?

A 40%

B 60%

C 50%

D 70%

Correct Answer: A. 40%

EXPLANATION

Maximum efficiency is Carnot efficiency = 1 - (T_cold/T_hot) = 1 - (300/500) = 0.4 = 40%

Test

Q.32 Easy Thermodynamics

Which process requires zero work to be done by the system?

A Isobaric process

B Isochoric process

C Isothermal process

D Adiabatic process

Correct Answer: B. Isochoric process

EXPLANATION

In an isochoric (constant volume) process, W = ∫PdV = 0 because volume does not change.

Test

Q.33 Easy Thermodynamics

The entropy of a reversible adiabatic process is:

A Increases

B Decreases

C Remains constant

D Becomes negative

Correct Answer: C. Remains constant

EXPLANATION

A reversible adiabatic process is also called isentropic, meaning entropy remains constant (ΔS = 0).

Test

Q.34 Easy Thermodynamics

For an ideal gas undergoing an isothermal process, the change in internal energy is:

A Maximum

B Zero

C Negative

D Positive

Correct Answer: B. Zero

EXPLANATION

In an isothermal process, temperature is constant. For an ideal gas, internal energy depends only on temperature, so ΔU = 0.

Test

Q.35 Easy Thermodynamics

The First Law of Thermodynamics is a statement of conservation of:

A Momentum

B Energy

C Entropy

D Enthalpy

Correct Answer: B. Energy

EXPLANATION

The First Law of Thermodynamics states that energy cannot be created or destroyed, only converted from one form to another.

Test

Q.36 Easy Thermodynamics

Which of the following is an intensive property in thermodynamics?

A Temperature

B Mass

C Volume

D Weight

Correct Answer: A. Temperature

EXPLANATION

Temperature is an intensive property as it does not depend on the quantity of matter. Mass, volume, and weight are extensive properties.

Test

1 2 3 4

All Subjects & Topics

Govt. Exams

Entrance Exams

Teacher Exams

Subjects

Quick Links

Mechanical Engineering Thermodynamics

Mechanical Engineering
Thermodynamics