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Archimedes' Principle
"Archimedes’ principle: the magnitude of the buoyant force acting on a given body is equal to the weight of the fluid displaced by the body". This is represented with the equation:
F=pgv
Where:
F = Buoyant force of a given body,
p = density
v = Volume of the displaced fluid
g = acceleration due to gravity
Since p = ρf - ρg , where pf is the density of the fluid and pg is the density of the object, the original formula can then be revised to:
F = (pf--pg)gV
Density (p) = mass x volume
Viscosity: internal resistance to flow (Schneider)
Due to this principle, a swimmer underneath the surface of the water will always be pushed upwards towards the surface. (McMullen)
F=pgv
Where:
F = Buoyant force of a given body,
p = density
v = Volume of the displaced fluid
g = acceleration due to gravity
Since p = ρf - ρg , where pf is the density of the fluid and pg is the density of the object, the original formula can then be revised to:
F = (pf--pg)gV
Density (p) = mass x volume
Viscosity: internal resistance to flow (Schneider)
Due to this principle, a swimmer underneath the surface of the water will always be pushed upwards towards the surface. (McMullen)
Centre of Volume
The centre of volume is "the point around which a body’s volume is equally distributed and at which the buoyant force acts." (Schneider) This is the reason as to why beginners learn how to do front and back floats, which are progressions to the common strokes.
Objects float because the pressure of water underneath pushes them up and acts as support. Gravity is cancelled out with the water pressure pushing upwards, and therefore balance the weight (force of gravity) that our bodies have that causes us to go downwards. Humans swim in a horizontal position as it allows us to spread our weight throughout our body and enables us to act like a raft. Simply by having some sort of experience around the water, it is obvious that it is much easier to float on our back than having an upright position in the deep end (in which you are left with no choice but to thread water, which is essentially kicking with a whip kick, egg beater, or scissor kick and having our arms come towards and away from each other continuously). Despite the constant fear that non-swimmers have of the possibility of drowning, it is actually a lot more difficult to sink downwards than they may think. People who have more fat are much more buoyant compared to skinny or muscular people because fat is less dense than muscle. (Woodford) However, also keep in mind that flotation relies on two factors: the swimmers' buoyancy and their weight. If their buoyancy is equal to their weight, they will float; however, when their buoyancy is greater than their weight, they will sink (Schneider).
Factors of Floating
The ability of a dense body to float relies on these 3 factors: buoyant force must be equal or greater than body weight, body position, and the torque that acts upon a floating body. (Schneider)