Mechanical Aptitude Mechanical Aptitude Fluid Dynamics Principles Questions and Answers 3

Question 1

Which factor does NOT directly affect the buoyant force on a submerged object?

Accepted Answer

Mass of the object

Answer

Buoyant force equals the weight of displaced fluid (fluid density x volume x gravity), so the object's mass does not directly determine buoyancy.

Question 2

Water flows through a horizontal pipe at a steady rate. If the pipe diameter is tripled, by what factor does the flow velocity change assuming the same volumetric flow rate?

Accepted Answer

Decreases to 1/9

Answer

Area increases by the square of the diameter ratio (3^2 = 9), so velocity decreases to 1/9 of the original to maintain the same flow rate.

Question 3

A siphon is used to transfer water from a higher tank to a lower tank. What primarily drives the flow?

Accepted Answer

Atmospheric pressure and gravity

Answer

A siphon works because atmospheric pressure pushes fluid up the shorter leg while gravity pulls it down the longer leg, sustaining continuous flow.

Question 4

If the Reynolds number for flow in a pipe exceeds approximately 4,000, the flow is generally classified as what?

Accepted Answer

Turbulent

Answer

A Reynolds number above approximately 4,000 indicates fully turbulent flow in pipe systems.

Question 5

A fire truck pumps water through a hose and out a nozzle. Why does the water exit the nozzle at a much higher speed than it travels through the hose?

Accepted Answer

The nozzle has a smaller cross-sectional area than the hose

Answer

The nozzle's smaller area forces the same volume of water through a tighter space, increasing velocity according to the continuity equation.

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Mechanical Aptitude Fluid Dynamics Principles Questions and Answers 3