Unit 8 · 8.3 — Fluids and Newton's Laws

Everything to learn here

• Concept: Buoyancy arises from structural pressure differences; the hydrostatic pressure on the deeper bottom of a submerged object is always greater than the pressure on its top, creating a net upward force.
• Concept: Archimedes' Principle mandates that the total upward buoyant force exactly equals the total gravitational weight of the displaced fluid.
• Concept: Whether an object sinks, floats, or remains neutrally suspended is determined by the application of Newton's Second Law comparing gravitational force to the buoyant force.
• Equation: $$Fb=rh{o}_{f}luid\cdot V_{d}isplaced\cdot g$$
• Vocabulary: Buoyant Force (Fb) — The net upward vector force resulting from the surrounding fluid's pressure gradient.
• Vocabulary: Displaced Fluid — The geometric volume of fluid physically pushed out of the way by a submerged or partially submerged object.
• Skill: Creating Representations — Drawing accurate FBDs for submerged objects, showing Fb pointing up and Fg pointing down from the center of mass, scaling vectors to reflect acceleration or equilibrium.
• Concept: Newton’s laws of motion explain how forces acting on fluid particles result in their acceleration and overall movement.

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