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Pressure clarified. Pressure. What affects the pressure of a liquid? Gravity The density of the liquid The depth of the liquid. Pressure.
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Pressure • What affects the pressure of a liquid? • Gravity • The density of the liquid • The depth of the liquid
Pressure • Remember when I told you that pressure increased when you went farther down in the water… Well how does pressure relate to depth if pressure is force divided by area…
Pressure Equation Derived • P = F/A = force / area • Force/area = weight/area • Weight/area = weight density xvolume/area • = weight density x area x depth / area • = weight density x depth • THEREFORE: Pressure = weight density x depth **Weight density = density x gravity
Buoyant Force • Upward force that the fluids exerts • Opposite to gravity • Recall that forces are greater at greater depth • Thus, results from the difference of the upward and downward forces applied to a submerged object • Since the upward forces come from deeper in the liquid, the object is pushed up making is lighter
Buoyant Force Bigger Buoyant force in deeper liquids
Why do I feel lighter in water? • Because the buoyant force pushes up against gravity, making you seem lighter in water
Archimedes’ Principle • An immersed object is buoyed up by force equal to the weight of the fluid it displaced.
Displaced Water • the amount of liquid pushed aside by a submerged object • volume of liquid displaced equals the volume of the submerged object • the depth of the liquid is increased by the submerged object because the liquid rises.
Archimedes Principle Common language: The buoyant force of an object is equal to the weight of the displaced The weight of this volume is equal to the buoyant force.
Weight: Sink or Float • When the weight is less than the buoyant force, the object will… rise to the surface and floats • When the weight of a submerged object is greater than the buoyant force… it sinks
See how the buoyant force works Object floats because the buoyant force is bigger than weight Sinks. Why?
Density: Sink or Float? • If the object is less dense than water… it floats • If the object is more dense than water… it sinks • If it has the same density as water, it doesn’t sink or float… like a fish