List of top Mechanical Engineering Questions

Assertion (A): In heating and dehumidification of air, relative humidity of air decreases.
Reason (R): Sensible heating causes enthalpy to decrease.
In light of the above statements, choose the correct answer from the options given below.

The instantaneous centre of a sliding body moving on a stationary curved surface lies at

The shape factor of a hemispherical body placed on a flat surface with respect to itself is

Given below are two statements:
Statement (I): The heat transfer coefficient for air in free convection varies between 5 to 30 W/m²·K.
Statement (II): The heat transfer coefficient of steam during condensation lies between 5000 to 110000 W/m²·K.
In light of the above statements, choose the most appropriate answer from the options given below.

A thermo flask is

2 kg of air is contained in a closed system at a pressure of 2 bar and 0.5 m³. It undergoes an isobaric expansion till the final volume becomes 0.6 m³. The work transfer (in kJ) during the process is:

Given below are two statements, one is labelled as Assertion (A) and the other one labelled as Reason (R):
Assertion (A): The Clausius statement of second law of thermodynamics states that it is impossible to transfer heat from a body at low temperature to a body at high temperature without the aid of external work.
Reason (R): Heat always flows from low temperature to high temperature.
In light of the above statements, choose the correct answer from the options given below:

A system at 500 K receives 7200 kJ/min of heat from a source at 1000 K The ambient temperature is 300 K The system and source temperature remain constant during heat transfer The decrease in available energy due to heat transfer through finite temperature difference is

Lumped Heat capacity analysis can be applied to a system when

Given below are two statements:
Statement (A): The flow in a pipe is turbulent when the Reynolds’ Number is more than 4000.
Statement (R): The flow in a pipe is turbulent at entry and slowly changes to laminar along the length of the pipe.
In light of the above statements, choose the correct answer from the options given below:

Consider the following statements about the flow in a convergent-divergent nozzle operating under design conditions:

1. In the divergent section, pressure is higher than the pressure in the convergent section.
2. The pressure at the throat is equal to critical pressure.
3. The pressure in the convergent section reduces.
4. The flow is subsonic in the convergent section and supersonic in the divergent section.

Choose the correct answer from the options given below.

Given below are two statements one is labelled as Assertion A and the other one labelled as Reason R

The vacuum in a closed container is 50 mm of Hg The absolute pressure in the container is

What are the number of numbers possible divisible by 3 if we choose 4 numbers from the set S = {4,5,7,8,9}