Question

For a submarine, identify when the water will be exerting a buoyant force on it. Assume that neither the volume of the submarine nor the density of the water change. Choose all that apply.

A. when it is full of cargo, fully submerged, and resting on the bottom at a depth of 74 m.
B. When it is full of cargo and fully submerged at a depth of 37 m.
C. When it is empty and floating on the surface.
D. When it is empty and fully submerged at a depth of 37 m.
E. When it is empty, fully submerged, and resting on the bottom at a depth of 74 m.
F. When it is in dry dock and no part of it is submerged in water.
G. when it is full of cargo and floating on the surface.

Answer 1

The buoyant force on a submarine is present when the submarine either fully or partially displaces water. This force acts when the submarine is submerged at any depth or floating on the surface, full of cargo or empty, but not when it is resting on the bottom or in dry dock.

Step-by-step explanation:

The buoyant force exerted by a fluid on an object within it acts at all times, regardless of whether the object is floating, submerged, or resting on the bottom, as long as the object is in contact with the fluid. According to Archimedes' principle, the buoyant force is equal to the weight of the fluid displaced by the object. Therefore:

• B. When it is full of cargo and fully submerged at a depth of 37 m.
• C. When it is empty and floating on the surface.
• D. When it is empty and fully submerged at a depth of 37 m.
• E. When it is empty, fully submerged, and resting on the bottom at a depth of 74 m.
• G. when it is full of cargo and floating on the surface.

These scenarios indicate that the submarine would be in contact with water and displace some amount of it, which would result in a buoyant force.

However, when the submarine is in dry dock (F) or resting on the bottom while fully loaded (A), the water is not exerting a buoyant force because in the first scenario it is not in contact with water, and in the second, even though it is in contact with the water, it does not displace it, as it would be supported by the solid ground beneath and thus not floating.