OAR OAR Mechanical Comprehension: Fluids 2

Question 1

A hydraulic jack uses a small piston of area 2 in² and a large piston of area 20 in². If you apply 50 lbs to the small piston, what force does the large piston exert?

Accepted Answer

500 lbs

Answer

50 lbs

Answer

250 lbs

Answer

1000 lbs

Question 2

Water flows through a horizontal pipe that narrows from 4 in² to 1 in² cross-section. How does the velocity change at the narrow section?

Accepted Answer

Velocity quadruples

Answer

Velocity decreases by half

Answer

Velocity doubles

Answer

Velocity stays the same

Question 3

Which of the following best describes gauge pressure?

Accepted Answer

Pressure measured relative to atmospheric pressure

Answer

Pressure measured relative to a perfect vacuum

Answer

The pressure exerted only by liquids

Answer

The pressure at the deepest point of a fluid

Question 4

A solid steel cube and a hollow steel cube of the same outer dimensions are submerged in water. Which experiences greater buoyant force?

Accepted Answer

Both experience the same buoyant force

Answer

The solid cube

Answer

The hollow cube

Answer

It depends on the water temperature

Question 5

Oil with a specific gravity of 0.85 floats on water. If the oil layer is 10 inches thick, what pressure (in psi) does it add at the oil-water interface? (Water weighs 0.0361 psi/in)

Accepted Answer

0.307 psi

Answer

0.361 psi

Answer

0.425 psi

Answer

0.850 psi

Question 6

In Bernoulli's equation for an ideal fluid, when fluid flows faster its pressure:

Accepted Answer

Decreases

Answer

Increases proportionally

Answer

Remains constant

Answer

Doubles

Question 7

A dam holds back water 30 feet deep. At what depth below the surface is the pressure greatest?

Accepted Answer

At 30 feet

Answer

At the surface

Answer

At 15 feet

Answer

Pressure is uniform throughout