Freefall is falling under gravity, weightlessness is freefall feeling no weight, a dam is wider at the bottom to distribute pressure, swimming is easier in the sea due to buoyancy.
Freefall is when an object falls only under the influence of gravity, experiencing an acceleration due to gravity. In weightlessness, an object is in freefall but also experiences a sensation of zero weight due to being in a state of continuous freefall around a planet or celestial body.
The wall of a dam is wider at the bottom to withstand the pressure exerted by the water it holds. The wider base distributes the force over a larger area, reducing the pressure at any specific point on the dam.
It is easier to swim in the sea than in a river because the sea has higher buoyancy due to its salt content which makes it easier for a person to float and swim. In contrast, fresh river water has lower buoyancy.
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