Fluid Mechanics

A solid cube is fully submerged in water. Which of the following determines the magnitude of the buoyant force acting on the cube?

• The mass of the cube

• The volume of water displaced by the cube

• The density of the cube material

• The depth at which the cube is submerged

Two objects have identical volumes but different masses. When both are completely submerged in the same liquid, how do their buoyant forces compare?

• The denser object experiences greater buoyant force

• The less dense object experiences greater buoyant force

• Both experience equal buoyant forces

• The buoyant forces depend on the shape of each object

A ship floats on saltwater while carrying cargo. When the ship enters a freshwater river, what happens to the ship's draft (depth of submersion)?

• The draft decreases because freshwater is less dense than saltwater

• The draft increases because freshwater is less dense than saltwater

• The draft remains unchanged because buoyancy is independent of fluid density

• The draft increases because the ship becomes heavier

A spherical balloon filled with helium is submerged underwater and held in place by a string. Which statement best explains why the balloon pulls upward on the string?

• Helium molecules repel water molecules

• The buoyant force exceeds the weight of the balloon and helium combined

• Water pressure creates an upward force on the balloon's surface

• The balloon's material is naturally buoyant

An object is placed in a container of water, and the water level rises from 500 mL to 625 mL. Based on this observation, what can be determined about the buoyant force?

• The buoyant force equals the weight of 125 mL of water

• The buoyant force cannot be determined without knowing the object's mass

• The buoyant force depends on how long the object remains submerged

• The buoyant force is greater than the object's weight

A wooden block floats in water with 70% of its volume submerged. If this same block were placed in a denser fluid, what would likely happen?

• A) A smaller percentage of the block would be submerged

• B) A larger percentage of the block would be submerged

• C) The entire block would sink regardless of fluid density

• D) The percentage submerged would remain exactly 70%

An ice cube floats in fresh water, partially submerged. When it melts, what happens to the water level in the container?

• The water level rises because the melted ice occupies more space

• The water level drops because the melted ice occupies less space

• The water level remains essentially unchanged because the buoyant force equals the ice's weight

• The water level rises significantly, then drops as the water warms

A submarine adjusts its buoyancy by flooding or emptying ballast tanks. To descend, the submarine must ensure that:

• The buoyant force equals the submarine's weight

• The buoyant force exceeds the submarine's weight

• The weight of the submarine exceeds the buoyant force

• The submarine's density equals the water's density

A diver holds a neutral buoyancy position underwater, neither sinking nor rising. Which of the following is occurring?

• The diver's density equals the water's density

• The buoyant force equals the diver's weight

• The water pressure is balanced on all sides of the diver

• Both A and B are correct

A hot air balloon rises through the atmosphere. How does Archimedes' principle apply to explain this phenomenon?

• The hot air inside creates a pressure that pushes the balloon upward

• The buoyant force from displaced air exceeds the weight of the balloon and hot air combined

• The balloon's material is naturally lighter than air

• Heat energy directly propels the balloon upward