Which of the following fluids is classified as non-Newtonian?

The correct answer is C: Ketchup. Ketchup is a pseudoplastic fluid whose viscosity changes with shear rate. Water, air, and mercury are Newtonian fluids with constant viscosity.

Which of the following statements about streamline flow is correct?

The correct answer is B: Streamlines are paths followed by fluid particles. Streamlines represent the paths followed by individual fluid particles in steady flow. They cannot intersect, and velocity is always tangential to streamlines.

A carnot engine operates between 600 K and 300 K. The maximum possible efficiency is:

The correct answer is B: 50%. Carnot efficiency = 1 - (T_cold/T_hot) = 1 - (300/600) = 0.5 = 50%

A horizontal jet of 0.02 m² cross-section with velocity 8 m/s strikes a curved vane and is deflected 60°. What is the force on the vane in the direction of jet?

The correct answer is C: 6.40 kN. Force = ρAV²(1 - cos60°) = 1000 × 0.02 × 64 × 0.5 = 6.4 kN. The deflection angle affects the force component.

In power screw design, what does the 'efficiency' of a screw represent?

The correct answer is A: Ratio of output power to input power. Screw efficiency = (Load × pitch)/(2π × effort × radius). It represents the ratio of useful work output to the energy input, typically ranging from 25-90%.

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Mechanical Engineering
Thermodynamics

Thermodynamics, hydraulics, machine design

36 Q 3 Topics Take Mock Test

Difficulty: All Easy Medium Hard 1–10 of 36

Topics in Mechanical Engineering

All Thermodynamics 100 Fluid Mechanics 79 Machine Design 80

Q.1 Easy Thermodynamics

According to the Second Law of Thermodynamics, for a spontaneous process in an isolated system, the entropy must:

A Decrease

B Remain constant

C Increase

D First increase then decrease

Correct Answer: C. Increase

EXPLANATION

Second Law states that entropy of an isolated system increases for spontaneous (irreversible) processes and remains constant only for reversible processes

Test

Q.2 Easy Thermodynamics

In a closed system, 50 kJ of heat is added and 30 kJ of work is done by the system. The change in internal energy is:

A 20 kJ

B -20 kJ

C 80 kJ

D -80 kJ

Correct Answer: A. 20 kJ

EXPLANATION

From First Law: ΔU = Q - W = 50 - 30 = 20 kJ (taking work done by system as positive)

Test

Q.3 Easy Thermodynamics

For an ideal gas, if both pressure and volume are doubled, the temperature ratio T₂/T₁ will be:

A 1

B 2

C 4

D 0.5

Correct Answer: C. 4

EXPLANATION

Using ideal gas law PV = nRT: T₂/T₁ = (P₂V₂)/(P₁V₁) = (2P₁ × 2V₁)/(P₁V₁) = 4

Test

Q.4 Easy Thermodynamics

Which process is represented when a gas is compressed without any heat transfer to or from surroundings?

A Isothermal process

B Isobaric process

C Adiabatic process

D Isochoric process

Correct Answer: C. Adiabatic process

EXPLANATION

An adiabatic process has no heat transfer (Q = 0) between the system and surroundings

Test

Q.5 Easy Thermodynamics

Which law states that the total energy of an isolated system remains constant?

A Second Law of Thermodynamics

B First Law of Thermodynamics

C Third Law of Thermodynamics

D Zeroth Law of Thermodynamics

Correct Answer: B. First Law of Thermodynamics

EXPLANATION

The First Law of Thermodynamics is the conservation of energy principle for thermodynamic systems

Test

Q.6 Easy Thermodynamics

In a constant volume process (isochoric), if temperature increases from 300 K to 600 K, the pressure ratio P₂/P₁ will be:

A 0.5

B 1.0

C 2.0

D 4.0

Correct Answer: C. 2.0

EXPLANATION

For isochoric process: P/T = constant, so P₂/P₁ = T₂/T₁ = 600/300 = 2.0

Test

Q.7 Easy Thermodynamics

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

A Isentropic process

B Isobaric process

C Isochoric process

D Isothermal process

Correct Answer: B. Isobaric process

EXPLANATION

The Diesel cycle has constant pressure heat addition (isobaric process) between the initial compression and subsequent expansion, distinguishing it from the Otto cycle

Test

Q.8 Easy Thermodynamics

A heat engine operates between two thermal reservoirs at temperatures 600 K and 300 K. What is the maximum possible efficiency of this engine?

A 25%

B 50%

C 75%

D 100%

Correct Answer: B. 50%

EXPLANATION

Maximum efficiency of a heat engine = 1 - (T_cold/T_hot) = 1 - (300/600) = 0.50 or 50% (Carnot efficiency)

Test

Q.9 Easy Thermodynamics

Which of the following statements about entropy is INCORRECT?

A Entropy is a measure of molecular disorder or randomness

B Entropy always increases for an irreversible adiabatic process

C Entropy of a reversible isothermal process equals Q/T

D Entropy of the universe decreases for spontaneous processes

Correct Answer: D. Entropy of the universe decreases for spontaneous processes

EXPLANATION

The Second Law states entropy of the universe INCREASES (ΔS_universe > 0) for spontaneous/irreversible processes, not decreases.

Test

Q.10 Easy Thermodynamics

The relationship between specific heats Cp - Cv for an ideal gas is:

A Cp - Cv = R

B Cp - Cv = 2R

C Cp = Cv (they are equal)

D Cp - Cv = R/M where M is molar mass

Correct Answer: A. Cp - Cv = R

EXPLANATION

Mayer's relation: Cp - Cv = R (per mole). This is fundamental for ideal gases.

Test

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