OAR OAR Mechanical Comprehension: Fluids 4

Question 1

Which of the following is an example of a non-Newtonian fluid?

Accepted Answer

Ketchup

Answer

Ketchup is a shear-thinning non-Newtonian fluid — its viscosity decreases under stress (like shaking the bottle).

Question 2

A pipe carrying water branches into two equal pipes. If the flow rate in the main pipe is 8 gal/min, what is the flow rate in each branch?

Accepted Answer

4 gal/min

Answer

Conservation of mass requires the total flow to be preserved: 8 gal/min splits equally into 4 gal/min per branch.

Question 3

What is cavitation in a fluid system?

Accepted Answer

Buildup of air bubbles at the pump inlet that collapse when pressure rises, causing damage

Answer

Cavitation occurs when local pressure drops below vapor pressure, forming bubbles that collapse violently and erode surfaces.

Question 4

A hydraulic system transmits 2,000 lbs of force through fluid. If there are no losses, the work done by the input piston equals the work done by the output piston because:

Accepted Answer

Energy is conserved — force × distance is equal on both sides

Answer

Pascal's Law multiplies force but not energy; the output piston moves a shorter distance proportionally, preserving work (W = F × d).

Question 5

Which condition must be true for Bernoulli's equation to apply without correction?

Accepted Answer

The flow must be steady and the fluid ideal (inviscid, incompressible)

Answer

Bernoulli's equation in its basic form assumes steady, incompressible, inviscid (frictionless) flow along a streamline.

OAR Test Practice Test

OAR Test Practice Test

OAR OAR Mechanical Comprehension: Fluids 4