Mechanical Aptitude Mechanical Aptitude Fluid Dynamics Principles 2

Question 1

A pipe narrows from 4 inches in diameter to 2 inches in diameter. How does the fluid velocity change at the narrower section?

Accepted Answer

It quadruples

Answer

By the continuity equation, when diameter halves the cross-sectional area quarters, so velocity must quadruple to maintain the same flow rate.

Question 2

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

Accepted Answer

Material composition of the object

Answer

Buoyant force equals the weight of displaced fluid, which depends on the object's volume and fluid density, not the object's material composition.

Question 3

Water flows through a horizontal pipe. At a section where the pipe widens, what happens to the pressure?

Accepted Answer

Pressure increases

Answer

According to Bernoulli's principle, where velocity decreases (wider pipe) pressure increases, since total energy is conserved.

Question 4

A hydraulic jack uses a small piston of area 2 in² and a large piston of area 20 in². If you apply 50 lb of force on the small piston, what force is produced at the large piston?

Accepted Answer

500 lb

Answer

Pascal's law states pressure is equal throughout: F_out = F_in × (A_out/A_in) = 50 × (20/2) = 500 lb.

Question 5

What is the primary reason turbulent flow creates more resistance than laminar flow in a pipe?

Accepted Answer

Turbulent flow creates chaotic mixing that dissipates more energy

Answer

Turbulent flow causes random, chaotic motion and eddies that convert kinetic energy into heat, significantly increasing energy loss and resistance.

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Test Practice Test

Mechanical Aptitude Mechanical Aptitude Fluid Dynamics Principles 2