Q: A diver descends to a depth of $$30\ \mathrm{m} in $$seawater ($$\rho = 1025\ \mathrm{kg/m}^3). $$What is the absolute pressure at this depth? (Assume atmospheric pressure $$P_{atm} = 1.0 \times 10^5$\ \mathrm{Pa}$$ and $$g = 9.8\ \mathrm{m/s}^2)$$

$$4.01 \times 10^5$\ \mathrm{Pa}$$

Q: A circular plug with area $$0.03\ \mathrm{m}^2 is $$used to seal the bottom of a water tank that is $$50\ \mathrm{m}$$ tall. What is the force on the plug due to the water? ($$\rho_{water} = 1000\ \mathrm{kg/m}^3$$, $$g = 9.8\ \mathrm{m/s}^2$$, $$P_{atm} = 1.0 \times 10^5$\ \mathrm{Pa})$$

$$1.58 \times 10^5$\ \mathrm{N}$$

Question 1

A hydraulic lift uses an input piston of area $$0.01\ \mathrm{m}^2$$ and an output piston of area $$0.5\ \mathrm{m}^2. If a $$force of $$200\ \mathrm{N} is $$applied to the input piston, what is the maximum weight (in newtons) that can be lifted by the output piston, assuming the system is ideal and frictionless?

Accepted Answer

$$10,000\ \mathrm{N}$$

Question 2

According to Pascal's First Law, what happens to the pressure at all points in an enclosed fluid when the pressure is increased at one point?

Accepted Answer

The pressure increases uniformly throughout the fluid.

Question 3

A diver descends to a depth of $$30\ \mathrm{m} in $$seawater ($$ho = 1025\ \mathrm{kg/m}^3). $$What is the absolute pressure at this depth? (Assume atmospheric pressure $$P_{atm} = 1.0 	imes 10^5$\ \mathrm{Pa}$$ and $$g = 9.8\ \mathrm{m/s}^2)$$

Accepted Answer

$$4.01 	imes 10^5$\ \mathrm{Pa}$$

Question 4

Which of the following best describes the buoyant force acting on a completely submerged object in a fluid?

Accepted Answer

It equals the weight of the fluid displaced by the object.

Question 5

A glass is filled with water to different heights: Glass A (10 cm), Glass B (20 cm), and Glass C (10 cm) but with a wider base. Which statement is correct about the pressure at the bottom of each glass?

Accepted Answer

The pressure at the bottom of Glass A and Glass C are equal.

Question 6

A circular plug with area $$0.03\ \mathrm{m}^2 is $$used to seal the bottom of a water tank that is $$50\ \mathrm{m}$$ tall. What is the force on the plug due to the water? ($$ho_{water} = 1000\ \mathrm{kg/m}^3$$, $$g = 9.8\ \mathrm{m/s}^2$$, $$P_{atm} = 1.0 	imes 10^5$\ \mathrm{Pa})$$

Accepted Answer

$$1.58 	imes 10^5$\ \mathrm{N}$$

Question 7

Which of the following statements about floating and sinking is correct?

Accepted Answer

An object floats if its average density is less than the fluid's density.

Question 8

A block is suspended in air and then fully submerged in water. Which of the following is true about the block's apparent weight when submerged?

Accepted Answer

The apparent weight decreases due to the upward buoyant force.

Question 9

A $$10\ \mathrm{kg}$$ object is completely submerged in a fluid of density $$800\ \mathrm{kg/m}^3. $$What is the magnitude of the buoyant force acting on the object? ($$g = 9.8\ \mathrm{m/s}^2$$, object volume $$= 0.015\ \mathrm{m}^3)$$

Accepted Answer

$$117.6\ \mathrm{N}$$

Question 10

A U-shaped tube is filled with water and open to the atmosphere at both ends. If the water levels at both ends are the same, what can you conclude about the pressure at the bottom of both arms?

Accepted Answer

The pressures at the bottom of both arms are equal.

Question 11

A wooden log with mass $$8\ \mathrm{kg}$$ floats in a lake. If the density of water is $$1000\ \mathrm{kg/m}^3$$, what is the volume of water displaced by the log? ($$g = 9.8\ \mathrm{m/s}^2)$$

Accepted Answer

$$0.008\ \mathrm{m}^3$$

Question 12

Which equation correctly expresses the pressure at a depth $$h$$ below the surface of a fluid open to the atmosphere?

Accepted Answer

$$P = P_{atm} + \rho g h$$

Question 13

A hydraulic press has an input piston with radius $$0.02\ \mathrm{m}$$ and an output piston with radius $$0.10\ \mathrm{m}. If a $$force of $$100\ \mathrm{N} is $$applied to the input piston, what is the output force? (Assume ideal conditions.)

Accepted Answer

$$2,500\ \mathrm{N}$$

Question 14

If an object is suspended inside a glass dome and the air is removed, what happens to the buoyant force acting on the object?

Accepted Answer

The buoyant force becomes zero.

Question 15

A cube of side $$0.1\ \mathrm{m} is $$completely submerged in water. What is the difference in pressure between the top and bottom faces of the cube? ($$\rho_{water} = 1000\ \mathrm{kg/m}^3$$, $$g = 9.8\ \mathrm{m/s}^2)$$

Accepted Answer

$$98\ \mathrm{Pa}$$

Question 16

Which of the following is NOT a correct application of Pascal's Law?

Accepted Answer

A fluid at rest in an open container has the same pressure at all depths.

Static Fluids: Pressure, Pascal’s Laws, and Buoyancy

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