Mechanical Aptitude Mechanical Aptitude Fluid Dynamics Principles Questions and Answers 2

Question 1

A pipe narrows from a 4-inch diameter to a 2-inch diameter. If water flows at 2 ft/s in the wider section, what is the approximate velocity in the narrower section?

Accepted Answer

8 ft/s

Answer

By the continuity equation, reducing the diameter by half reduces the area by a factor of four, so the velocity increases four times from 2 ft/s to 8 ft/s.

Question 2

Which principle explains why a shower curtain gets pulled inward when the water is running?

Accepted Answer

Bernoulli's principle

Answer

The fast-moving air created by the shower reduces pressure on the inside of the curtain, and higher outside pressure pushes it inward, which is explained by Bernoulli's principle.

Question 3

A hydraulic system has a small piston with an area of 5 sq in and a large piston with an area of 50 sq in. If 20 lbs of force is applied to the small piston, what force is exerted by the large piston?

Accepted Answer

200 lbs

Answer

By Pascal's principle, the force is multiplied by the ratio of piston areas: 20 lbs x (50/5) = 200 lbs.

Question 4

What happens to the flow rate in a pipe if the fluid viscosity doubles while all other factors remain constant?

Accepted Answer

Flow rate is reduced by half

Answer

According to the Hagen-Poiseuille equation, flow rate is inversely proportional to viscosity, so doubling viscosity halves the flow rate.

Question 5

A tank has two outlet holes at different heights. Which statement is correct about the water streams?

Accepted Answer

The lower hole produces a faster stream

Answer

By Torricelli's theorem, the exit velocity depends on the depth of fluid above the hole, so the lower hole has greater pressure and produces a faster stream.

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Mechanical Aptitude Fluid Dynamics Principles Questions and Answers 2