AP®PhysicsCollege BoardPhysics 1: Algebra-BasedExam QuestionsUnit 8: FluidsDensity & Pressure

Density & Pressure (College Board AP® Physics 1: Algebra-Based): Exam Questions

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Density & Pressure

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1
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A tank is filled to the top with oil of density 780 kg/m3 and then placed in a vacuum. The tank has a width of 0.25 m, a length of 30 m, and a depth of 4.6 m.

Which of the following is most nearly the pressure halfway down the depth of the tank?

  • 18 kPa

  • 35 kPa

  • 120 kPa

  • 300 kPa

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2
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A bottle is filled completely with water, as shown in the diagram below. Which of the points shown have the same pressure?

A completely full bottle of liquid has three points with pressures, P_A, P_B and P_C at varying depths. Point P_A is in the bottle's neck, 5 cm from the top. Point P_B the base of the bottle's neck is 10 cm below this point. Points P_B and P_C are both 5 cm below the base of the bottle's neck, on the same horizontal line.

  • PA and PB

  • PB and PC

  • PA and PC

  • PA, PB, and PC

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3
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Two identical containers underneath pistons both contain a volume V of fluid.
In one container, the fluid is a gas. In the other it is an ideal fluid.

Which of the following correctly describes how the volume of each fluid changes when a force F is applied downwards on each piston?

  • Ideal fluid volume does not change.
    Gas volume decreases.

  • Ideal fluid volume decreases.
    Gas volume does not change.

  • Ideal fluid volume decreases.
    Gas volume decreases.

  • Ideal fluid volume does not change.
    Gas volume does not change.

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4
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Which of the following correctly describes an ideal fluid?

  • It has a high viscosity and is compressible.

  • It is incompressible and has zero viscosity.

  • It exhibits high density and negligible surface tension.

  • It has fixed shape and high resistance to flow.

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5
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A container holds water at a depth of 5.0 m. The atmospheric pressure is 1.0×105 Pa, and the density of water is 1000 kg/m3. What is the absolute pressure at the bottom of the container?

  • 1.3×105 Pa

  • 1.5×105 Pa

  • 1.7×105 Pa

  • 2.0×105 Pa

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1
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Anglerfish can live at a depth of 800 m below the surface of the ocean.

Which of the following is most nearly the number of atmospheres of pressure an anglerfish experiences at this depth?

  • 10

  • 50

  • 60

  • 80

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2
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A sample of oil in a cylindrical container is placed on a mass balance. The cylinder has a mass of 125 g and a radius of 4.2 cm. There is a bubble with a radius of 3.0 cm midway up the cylinder of oil. The reading on the balance is 1.0 kg, and the oil fills the measuring cylinder up to a height of 25 cm.

Which of the following is most nearly the density of the oil?

  • 600 kg/m3

  • 700 kg/m3

  • 900 kg/m3

  • 1000 kg/m3

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3
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A U-shaped tube contains two liquids and is open-ended on both sides.

U shaped tube with two liquids. Points 1 and 2 are at the same height, points 3 and 4 are at the same height but lower than points 1 and 2. Points 1 and 3 are in the left side of the tube, points 2 and 4 are in the right side of the tube. Point 1 lies within the lower density liquid, all other points are in the higher density liquid.

The liquid with density rho is in the left side of the tube, resting on top of the liquid with density 12 rho.

Points 1 and 2 have the same height. The top of liquid rho is 30 cm about point 1, and the top of liquid 12 rho is 3 cm above point 2.

Points 3 and 4 have the same height.

The system is in equilibrium.

Which of the following sets of relationships is true between the gauge pressures of the points shown?

  • P subscript 1 space less than space P subscript 2 and P subscript 3 space equals space P subscript 4

  • P subscript 1 space equals space P subscript 2 and P subscript 3 space equals space P subscript 4

  • P subscript 1 space greater than space P subscript 2 and P subscript 3 space greater than space P subscript 4

  • P subscript 1 space greater than space P subscript 2 and P subscript 3 space less than space P subscript 4

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4
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A rectangular solid block of dimensions 2 space straight m space times space 1 straight m space times space 0.5 space straight m is submerged in water (rho space equals space 1000 space kg divided by straight m cubed ) such that its shortest side is vertical.

If the block is completely submerged, which of the following is the difference in pressure between the top and bottom surfaces of the block?

  • 5000 Pa

  • 9800 Pa

  • 14700 Pa

  • 19600 Pa

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5
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A container is filled with two immiscible liquids: oil (rho = 800 kg/m3, height = 0.5 m) and water (rho = 1000 kg/m3, height = 1.0 m).

Which of the following is the total pressure at the bottom of the container? Assume atmospheric pressure is 1.0×105 Pa.

  • 1.37×104 Pa

  • 1.04×105 Pa

  • 1.13×105 Pa

  • 1.14×105 Pa

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1
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A vase floats with its lower section in water and its upper section in oil. The distance from the top of the vase to the oil-water interface is labeled x. The surface on the bottom of the vase, in water, is labeled S. The water has density 1000 kg / m^3, the oil has density 500 kg / m^3. The height of the oil is 3.3 m and the height of the water is 6.7 m. Outside the tank, the atmosphere is labeled sea level atmosphere.

A 2.0 m tall vase floats at an interface between oil and water in a large tank, as shown in the figure. The height of oil above the water is 3.3 m and the height of the vase above the water is x. The density of the oil is 800 kg/m3 and the density of the water is 1000 kg/m3.

If the pressure at the lower surface S of the vase is 144 kPa, which of the following is most nearly the value of x?

  • 0.12 space straight m

  • 0.24 space straight m

  • 1.2 space straight m

  • 1.8 space straight m

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2
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Two identical tanks filled to the top with water contain a ball bearing. Each ball bearing experiences the same absolute pressure. One tank is at an altitude of 1 km, where atmospheric pressure is 0.88 P subscript a t m end subscript, and the other tank is at sea level.

Which of the following is most nearly the difference between the depths of the ball bearings?

  • 1.2 ×10−5 m

  • 1.2 m

  • 5.3 m

  • 19 m

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3
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Side view shows the piston over a container of water. The point indicated is 125 cm below the piston. View from above shows that each side of the hexagonal piston is 5 cm wide.

A volume of water is contained in a container below a piston as shown in the figure above. The piston is a regular hexagon with side length 5 cm and the container is a hexagonal prism.

When a force of 160 N is applied to the piston, what is the change in pressure at the point shown, which is 125 cm below the piston?

The density of the water is 1000 kg/m3.

  • 1.52 Pa

  • 12.2 kPa

  • 24.6 kPa

  • 49.3 kPa

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4
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A container is filled with two immiscible fluids. One layer is oil with a density of 750 kg/m3 and a height of 2.0 m, the other is water, with a density of 1000 kg/m3 and a height of 3.0 m.

At a certain point in the container, the absolute pressure is 1.43 × 105 Pa.

Which of the following is the correct height of this point above the bottom of the container?

  • 0 m

  • 0.20 m

  • 0.50 m

  • 2.0 m

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5
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A closed circular hatch with a diameter of 30 cm is located at the bottom of a cylindrical tank (radius 150 cm), which is filled with 42.4 m3 of water (rho = 1000 kg/m3).

Which of the following is closest to the total force experienced by the hatch?

Atmospheric pressure is 1.0×105 Pa.

  • 2.5 kN

  • 5.0 kN

  • 10 kN

  • 20 kN

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