Q: A diver descends to a depth of 20 meters in seawater (density $$\rho = 1025\ \text{kg/m}^3). $$What is the gauge pressure at this depth? (Assume $$g = 9.8\ \text{m/s}^2)$$

$$P = \rho g h = 1025 \times 9.8 \times 20 = 201,000\ \text{Pa}$$

Question 1

Which of the following best describes the physical meaning of pressure in a fluid?

Accepted Answer

Pressure is the force exerted by a fluid per unit area.

Question 2

A diver descends to a depth of 20 meters in seawater (density $$ho = 1025\ 	ext{kg/m}^3). $$What is the gauge pressure at this depth? (Assume $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$P = ho g h = 1025 	imes 9.8 	imes 20 = 201,000\ 	ext{Pa}$$

Question 3

Which equation expresses Boyle's Law for an ideal gas?

Accepted Answer

$$P V = 	ext{constant}$$

Question 4

A weather balloon rises from sea level to an altitude where the atmospheric pressure is half its original value. Assuming the temperature remains constant, what happens to the volume of the balloon?

Accepted Answer

The volume doubles.

Question 5

Which of the following best describes the Karman Line?

Accepted Answer

It is the boundary between Earth's atmosphere and outer space, located at 100 km altitude.

Question 6

A cube of wood (density $$600\ 	ext{kg/m}^3) $$floats in water (density $$1000\ 	ext{kg/m}^3). $$What fraction of the cube's volume is submerged?

Accepted Answer

$$\frac{600}{1000} = 0.6$$

Question 7

Which principle explains why an airplane wing generates lift?

Accepted Answer

Bernoulli's Principle

Question 8

A fluid flows through a horizontal pipe that narrows from a wide section to a narrow section. According to Bernoulli's equation, what happens to the fluid's speed and pressure in the narrow section?

Accepted Answer

Speed increases, pressure decreases.

Question 9

A submarine is submerged at a depth where the water pressure is $$3 	imes 10^5$\ 	ext{Pa}. If $$the atmospheric pressure above is $$1 	imes 10^5$\ 	ext{Pa}$$, what is the absolute pressure experienced by the submarine?

Accepted Answer

$$4 	imes 10^5$\ 	ext{Pa}$$

Question 10

Which equation represents the relationship between pressure, force, and area?

Accepted Answer

$$P = \frac{F}{A}$$

Question 11

A hydraulic lift uses a small piston of area $$0.01\ 	ext{m}^2$$ and a large piston of area $$0.1\ 	ext{m}^2. If a $$force of $$100\ 	ext{N} is $$applied to the small piston, what is the maximum weight that can be lifted by the large piston (neglecting losses)?

Accepted Answer

$$1000\ 	ext{N}$$

Question 12

Which of the following statements about compressible fluids is correct?

Accepted Answer

Compressible fluids can change their density significantly with pressure.

Question 13

A fluid is flowing steadily through a pipe. If the cross-sectional area decreases, what happens to the velocity of the fluid, assuming incompressible flow?

Accepted Answer

Velocity increases.

Question 14

Which equation expresses the continuity equation for incompressible fluids?

Accepted Answer

$$A_1$$ $$v_1$$ = $$A_2$$ $$v_2$$

Question 15

A hot air balloon rises because the air inside is less dense than the air outside. Which principle explains this phenomenon?

Accepted Answer

Archimedes' Principle

Question 16

A fluid is at rest. Which law states that the pressure at a point is the same in all directions?

Accepted Answer

Pascal's Law

Question 17

A tank contains water open to the atmosphere. If a hole is made at a depth $$h$$ below the surface, what is the speed of water exiting the hole? (Neglect viscosity and assume $$g is $$gravity)

Accepted Answer

$$v = \sqrt{2gh}$$

Question 18

A person drinks through a straw. Which principle allows the liquid to rise up the straw when the person reduces the pressure inside their mouth?

Accepted Answer

Atmospheric pressure pushes the liquid up the straw.

Question 19

A fluid flows through a pipe with varying elevation. According to Bernoulli's equation, which term accounts for changes in height?

Accepted Answer

$$\rho g h$$

Question 20

A sealed container of gas is compressed to half its original volume at constant temperature. What happens to the pressure inside the container?

Accepted Answer

Pressure doubles.

Fluid Mechanics: Pressure, Buoyancy, and Bernoulli's Principle

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