Mechanical Aptitude Test Mechanical Aptitude Heat Transfer and Thermodynamics Questions and Answers 2

Question 1

The First Law of Thermodynamics is best described as:

Accepted Answer

Energy cannot be created or destroyed, only converted

Answer

The First Law is the conservation of energy: energy changes form but the total amount in a closed system remains constant.

Question 2

In a heat engine, after performing useful work, waste heat is exhausted into:

Accepted Answer

The cold reservoir

Answer

A heat engine absorbs heat from a hot reservoir, converts some to mechanical work, and must expel the remainder into a cold reservoir.

Question 3

A pressure cooker cooks food faster because increased pressure inside the vessel:

Accepted Answer

Raises the boiling point of water above 100°C

Answer

Higher pressure raises water's boiling point above 100°C, allowing food to cook at higher temperatures and therefore faster.

Question 4

Thermal expansion in metals means that when temperature increases, the metal will:

Accepted Answer

Expand as atomic vibrations increase spacing

Answer

Increased thermal energy causes metal atoms to vibrate with greater amplitude, increasing the average spacing between atoms and causing overall expansion.

Question 5

The Carnot efficiency of a heat engine depends on:

Accepted Answer

Only the absolute temperatures of the hot and cold reservoirs

Answer

Carnot efficiency = 1 − (Tc/Th) where Tc and Th are the absolute temperatures of the cold and hot reservoirs respectively — independent of the working fluid or engine design.

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Mechanical Aptitude Heat Transfer and Thermodynamics Questions and Answers 2