Fluids Review

The containers pictured above are each filled to a height h with the same fluid of uniform density. Which of the following is true of the pressures, pI , pII , pIII , and pIV , at the bottom of each respective container?

• pIII > pI > pII > pIV

• pI > pII > pIII > pIV

• pI = pII ; pIII > pIV

• pI > pII ; pIII = pIV

• They are all the same.

A hollow rectangular box is filled with a liquid and can be placed in any of the three orientations shown above. In which orientation will the fluid pressure at the bottom of the box be greatest, and why?

• Orientation X, because pressure at the bottom of a fluid is greater when the vertical height of the fluid is greater

• Orientation Y, because pressure at the bottom of a fluid is greater when the width times the height of the fluid is greater

• Orientation Z, because pressure at the bottom of a fluid is greater when the area of the bottom surface is greater

• All three orientations have the same pressure, because the weight of the fluid is the same in each case.

Two fluids of densities ρ and 2ρ are layered in a cylindrical container of diameter d, as shown above. The height of each fluid is h, and the pressure at the top of the column is P₀. What is the absolute pressure at the inside surface of the bottom of the container?

• 3ρgh

• 4ρgh

• 4ρg/πd²

• P_{0 +} 3ρgh

• P_{0 +} 12ρgh/πd²

A hydraulic press is shown

A force F₁ is applied to Piston₁. This creates a pressure P₁ on Piston₁, which increases the pressure uniformly throughout the much larger oil reservoir and results in a force F₂ on Piston₂. A pressure P₂ is therefore applied to Piston₂ . In the following problems, assume that the radius of Piston₂ ,r₂, is five times that of the radius of Piston₁, r₁.

How does the pressure P₁ compare to P₂

• Unknown

• P₂<P₁

• P₂= P₁

• P₂>P₁

A hydraulic press is shown

A force F₁ is applied to Piston₁. This creates a pressure P₁ on Piston₁, which increases the pressure uniformly throughout the much larger oil reservoir and results in a force F₂ on Piston₂. A pressure P₂ is therefore applied to Piston₂ . In the following problems, assume that the radius of Piston₂ ,r₂, is five times that of the radius of Piston₁, r₁.

If Piston₁ is moved a distance, x₁ by how much will Piston₂ move?

• X₂ =5X₁

• X₂ =10X₁

• X₂ = (1/5)X₁

• X₂=(1/25)X₁

A hydraulic press is shown

A force F₁ is applied to Piston₁. This creates a pressure P₁ on Piston₁, which increases the pressure uniformly throughout the much larger oil reservoir and results in a force F₂ on Piston₂. A pressure P₂ is therefore applied to Piston₂ . In the following problems, assume that the radius of Piston₂ ,r₂, is five times that of the radius of Piston₁, r₁.

To increase F₂ by four times, one must

• Increase P₁ by a factor of 2

• Increase r₂ by a factor of 2

• Increase r₁ by a factor of 2

A large rock thrown into a pool of water of uniform density becomes completely submerged and then sinks to the bottom. When is the buoyant force on the rock the greatest?

• When it just hits the water

• When it is partially underwater

• When it is completely underwater

• It cannot be determined without knowing the depth of the pool.

• It cannot be determined without knowing the mass of the rock.

A block is submerged in a container of liquid and held under the surface of the liquid by a string connected to the bottom of the container, as shown in the figure above. The tension in the string is not zero. How does the buoyant force F_B exerted by the liquid on the block compare to the block’s weight w ?

• F_B < w

• F_B = w

• F_B > w

• Either F_B <w or F_B >w, depending on the density of the liquid.

Three objects are placed in a tank of water, as shown: All of the objects have the same density, a density less than water, but they have different sizes as shown. When the objects are released, which one has the greatest acceleration?

• Object I

• Object II

• Object III

• All three objects will have the same

  acceleration

Tags

NGSS.HS-PS2-1

Three objects are placed in a tank ofwater, as shown below. The objects all have the same size, but they have different densities: ρI< ρII< ρIII. All of the densities are less than that of water. If all of the objects are released at the same time, which object reaches the surface first?

• Object I

• Object II

• Object III

• All three objects will have the same

  acceleration

Tags

NGSS.MS-PS2-5