OAR OAR Mechanical Comprehension: Fluids Questions and Answers 2

Question 1

A hydraulic jack has a small piston with an area of 2 sq in and a large piston with an area of 20 sq in. If 10 lb of force is applied to the small piston, what force is exerted by the large piston?

Accepted Answer

100 lb

Answer

By Pascal's principle, force multiplies by the area ratio: 10 × (20/2) = 100 lb.

Question 2

What happens to the buoyant force on a fully submerged object as it is pushed deeper into a fluid of uniform density?

Accepted Answer

It remains the same

Answer

Buoyant force depends only on displaced volume and fluid density, both of which remain constant as the object goes deeper.

Question 3

Water flows through a horizontal pipe that narrows from a diameter of 4 cm to 2 cm. How does the flow velocity change in the narrow section?

Accepted Answer

It quadruples

Answer

By the continuity equation, velocity is inversely proportional to cross-sectional area, and halving the diameter reduces area by a factor of four, so velocity quadruples.

Question 4

A submarine's hull must withstand greater pressure at deeper depths primarily because of which factor?

Accepted Answer

The increasing weight of the water column above it

Answer

Hydrostatic pressure increases with depth due to the weight of the fluid column above, as described by P = ρgh.

Question 5

An object with a density of 0.6 g/cm³ is placed in water (density 1.0 g/cm³). What fraction of the object's volume will be submerged?

Accepted Answer

60%

Answer

A floating object displaces fluid equal to its own weight, so the submerged fraction equals the ratio of object density to fluid density: 0.6/1.0 = 60%.

OAR Test Practice Test

OAR Test Practice Test

OAR OAR Mechanical Comprehension: Fluids Questions and Answers 2