Fluid Mechanics

Which of the following is a fluid?

• helium

• ice

• iron

• gold

Which of the following is NOT a fluid?

• carbon dioxide

• hydrogen

• seawater

• wood

Which of the following statements is NOT correct?

• A fluid flows.

• A fluid has a definite shape.

• Molecules of a fluid are free to move past each other.

• A fluid changes its shape easily.

How does a liquid differ from a gas?

• A liquid has both definite shape and definite volume, whereas a gas has neither.

• A liquid has definite volume, unlike a gas.

• A liquid has definite shape, unlike a gas.

• A liquid has definite shape, whereas a gas has definite volume.

When a gas is poured out of one container into another container, which of the following does NOT occur?

• The gas flows into the new container.

• The gas changes shape to fit the new container.

• The gas spreads out to fill the new container.

• The gas keeps its original volume.

For incompressible fluids, density changes little with changes in...

• depth.

• temperature

• pressure

• free-fall acceleration

A cube of wood with a density of 0.780 g/cm³ is 10.0 cm on each side. When the cube is placed in water, what buoyant force acts on the wood? (fresh water is 1.00 g/cm³)

• 7.65 x 10³ N

• 7.65 N

• 6.40 N

• 5.00 N

According to legend, to determine whether the king's crown is made of pure gold, Archimedes measured the crown's volume by determining how much water it displaced. The density of gold is 19.3 g/cm3^. If the crown's mass was 6.00 x 10² g, what volume of water would have been displaced if the crown was indeed made of pure gold?

• 31.1 cm³

• 1.81 x 10³ cm³

• 22.8 x 10³ cm³

• 114 x 10³ cm³

A buoyant force acts in the opposite direction of gravity. Therefore, which of the following is true of an object completely submerged in water?

• The net force on the object is smaller than the weight of the object.

• The net force on the object is larger than the weight of the object.

• The net force on the object is equal to the weight of the object.

• The object appears to weigh more than it does in air.

Which of the following statements about floating objects is correct?

• The object's density is greater than the density of the fluid on which it floats.

• The object's density is equal to the density of the fluid on which it floats.

• The displaced volume of the fluid is greater than the volume of the object.

• The buoyant force equals the object's weight.