Flash card - Upthrust in Fluids, Archimedes Principle and Floatation

Condition for Floating or Sinking

• Float: Upthrust ≥ Weight
• Sink: Weight > Upthrust

Formula for Upthrust

Upthrust = h × ρ × g × A
(= V × ρ × g)

Archimedes' Principle

Upthrust = Weight of liquid displaced

Relative Density (Basic)

RD = Density of substance ÷ Density of water at 4⁰C

Relative Density (in terms of Mass)

RD = Mass of substance ÷ Mass of equal volume of water at 4⁰C

Relative Density (in terms of Weight)

RD = Weight in air ÷ (Weight in air − Weight in water at 4°C)

Relative Density of a Liquid

RD = (Weight of body in air - weight of body in Liquid)
÷ (Weight in air- weight of body  in water)

Relation: Volume & Density

V_immersed / V_total = ρ_solid / ρ_liquid