OAR Mechanical Comprehension: Fluids Questions and Answers

Question 1

A hydraulic lift uses an enclosed fluid to lift a heavy object.
If a force of 100 N is applied to a small piston with an area of 5 cm², what is the maximum weight that can be lifted by a larger piston with an area of 100 cm²?

Accepted Answer

2,000 N

Answer

500 N

Answer

1,000 N

Answer

10,000 N

Question 2

A cargo ship is fully loaded in a freshwater port and then sails out into the saltwater ocean. Because saltwater is denser than freshwater, how will the ship's position in the water change, assuming no cargo is added or removed?

Accepted Answer

The ship will ride higher in the water.

Answer

The ship will sink lower in the water.

Answer

The ship's position will not change.

Answer

The ship will become unstable and list to one side.

Question 3

Water flows through a horizontal pipe that narrows at a certain point. According to Bernoulli's principle, what happens to the speed and pressure of the water as it passes through this constricted section?

Accepted Answer

The speed increases and the pressure decreases.

Answer

The speed increases and the pressure increases.

Answer

The speed decreases and the pressure increases.

Answer

The speed decreases and the pressure decreases.

Question 4

Three containers of different shapes are all filled with water to the same height. Which of the following statements about the pressure at the bottom of each container is true?

Accepted Answer

The pressure at the bottom of all three containers is the same.

Answer

The container with the largest volume has the greatest pressure at the bottom.

Answer

The container with the smallest bottom surface area has the greatest pressure.

Answer

The widest container has the greatest pressure at the bottom.

Question 5

Which of the following best defines the property of a fluid known as viscosity?

Accepted Answer

The fluid's internal resistance to flow.

Answer

The force exerted by the fluid per unit of surface area.

Answer

The ratio of an object's density to the fluid's density.

Answer

The weight of the fluid displaced by an object.

Question 6

A submarine is neutrally buoyant and suspended motionless at a depth of 100 meters. To begin ascending towards the surface without using its propellers, what action must it take?

Accepted Answer

Pump water out of its ballast tanks.

Answer

Pump water into its ballast tanks.

Answer

Angle its dive planes upwards.

Answer

Increase its internal air pressure.