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

$$P = 2.01 \times 10^5$ \ \mathrm{Pa}$$

Question 1

Which principle explains why the height (and pressure) of a column of liquid is independent of the shape of the container?

Accepted Answer

Pascal's Principle

Question 2

Given three containers of different shapes but filled to the same height with water, which statement is correct about the pressure at the bottom of each container?

Accepted Answer

The pressure is the same because it depends only on the height of the liquid.

Question 3

What is the formula for the buoyant force acting on a submerged object?

Accepted Answer

$$F_b = \rho_{fluid} V_{sub} g$$

Question 4

A block is fully submerged in water. If the atmospheric pressure is $$P_0$$ and the water density is $$\rho$$, what is the pressure at a depth $$h$$ below the surface?

Accepted Answer

$$P = P_0$ + \rho g h$$

Question 5

Which of the following best describes why a helium balloon rises in air?

Accepted Answer

The buoyant force is greater than the weight of the balloon.

Question 6

If an object floats in water with half its volume submerged, what can you conclude about the density of the object ($$\rho_{object}) $$compared to the density of water ($$\rho_{water}$$)?

Accepted Answer

$$\rho_{object} = 0.5 \rho_{water}$$

Question 7

A cube of side $$a is $$fully submerged in a liquid of density $$\rho. $$What is the magnitude of the net upward force (buoyant force) acting on the cube?

Accepted Answer

$$F_b = \rho a^3$ g$$

Question 8

Which of the following statements about pressure in a liquid is correct?

Accepted Answer

Pressure in a liquid acts in all directions.

Question 9

A solid object is placed in a fluid and sinks to the bottom. Which of the following is true?

Accepted Answer

The object's density is greater than the fluid's density.

Question 10

If the atmospheric pressure is $$P_0$$ and the pressure at the bottom of a submerged object is $$P_{bottom}$$, what is the net upward force due to the fluid on the object?

Accepted Answer

$$F_{net} = (P_{bottom} - P_{top})A$$

Question 11

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

Accepted Answer

$$P = 2.01 	imes 10^5$ \ \mathrm{Pa}$$

Question 12

Which of the following best explains why the pressure at the same depth is the same in all containers, regardless of their shape?

Accepted Answer

Pressure depends only on the height of the liquid column and the density of the liquid.

Question 13

A block of wood floats in oil with 60% of its volume submerged. If the density of oil is $$800 \ \mathrm{kg/m^3$}$$, what is the density of the wood?

Accepted Answer

$$\rho_{wood} = 480 \ \mathrm{kg/m^3$}$$

Question 14

If a cube is submerged in a fluid and the pressure at the top of the cube is $$P_{top}$$ and at the bottom is $$P_{bottom}$$, what is the net upward force on the cube?

Accepted Answer

$$F = (P_{bottom} - P_{top})A$$

Question 15

A metal block weighs 10 N in air and 7 N when fully submerged in water. What is the buoyant force acting on the block?

Accepted Answer

3 N

Fluid Pressure and Buoyancy: Study Notes

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