Mechanical Aptitude Test Mechanical Aptitude Fluid Dynamics Principles 1

Question 1

Water flows through a horizontal pipe at 3 ft/s with a pressure of 40 psi.
The pipe then widens, slowing the water to 1 ft/s.
According to Bernoulli's principle, what happens to the pressure in the wider section?

Accepted Answer

Pressure increases

Answer

Pressure decreases

Answer

Pressure remains the same

Answer

Pressure drops to zero

Question 2

A tank has a small hole at the bottom and is filled with water to a height of 9 feet. Using Torricelli's theorem, approximately how fast does water exit the hole? (g ≈ 32 ft/s²)

Accepted Answer

12 ft/s

Answer

24 ft/s

Answer

6 ft/s

Answer

18 ft/s

Question 3

A tank has a small hole at the bottom and is filled with water to a height of 2 feet. Using Torricelli's theorem, approximately how fast does water exit the hole? (g ≈ 32 ft/s²)

Accepted Answer

8 ft/s

Answer

11 ft/s

Answer

16 ft/s

Answer

4 ft/s

Question 4

Two pipes merge into one pipe. Pipe A carries fluid at 4 gallons per minute and Pipe B carries fluid at 6 gallons per minute. What is the total flow rate in the combined pipe, assuming incompressible flow?

Accepted Answer

10 gallons per minute

Answer

5 gallons per minute

Answer

24 gallons per minute

Answer

2 gallons per minute

Question 5

A fluid with a specific gravity of 0.8 is pumped through a pipe. Compared to water (specific gravity = 1.0) flowing at the same velocity in the same pipe, how does the dynamic pressure of this fluid compare?

Accepted Answer

It is 25% less than water's dynamic pressure

Answer

It is 25% greater than water's dynamic pressure

Answer

It is equal to water's dynamic pressure

Answer

It is 80% greater than water's dynamic pressure

Question 6

In a hydraulic jack, oil is pumped into a cylinder containing a piston of 10 square inches. If the oil pressure is 500 psi, what lifting force does the piston exert?

Accepted Answer

5,000 lbs

Answer

50 lbs

Answer

500 lbs

Answer

50,000 lbs

Question 7

Water flows upward through a vertical pipe from a lower elevation to one that is 10 feet higher. If the flow velocity stays constant, what happens to the fluid pressure at the higher elevation compared to the lower elevation?

Accepted Answer

Pressure decreases because the fluid must work against gravity

Answer

Pressure increases because the fluid is moving upward

Answer

Pressure stays the same because velocity is unchanged

Answer

Pressure doubles due to the elevation change