Unit 1: Fluids


Density - Mass per unit volume of a fluid, can also be stated as how "compact" something is.

Buoyancy - A force that's created when an object is submerged in a lfuid and is exerted upward on the object by the fluid.

Apparent mass - The mass an object appears to have when submerged in a fluid.

Atmospheric pressure = At sea level, this is 1.013 x 105 N/m2.

Archimedes' Principle - The buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by the object.

Bernoulli's Principle - Where the velocity of a fluid is high, the pressure is low, and where the velocity is low, the pressure is high.

Pascal's Principle - If an external pressure is applied to a confined fluid, the pressure at any point in the fluid increases by the same amount.


ρ = m/V - Used to find density. Density = mass/volume.

mg = ρVg - Another formula to find density. (Mass)(force of gravity) = (density)(volume)(force of gravity).

P = ρgh - Used to find pressure at a point. Pressure = (density of fluid)(force of gravity)(height of fluid above the point).

P = Po + ρgh - Used to find absolute pressure at a point. Absolute pressure = Atmospheric pressure + (density of fluid)(force of gravity)(height of fluid above the point).

A1V1 = A2V2 - The continuity equation, used to show that the volume of whatever goes through one cross sectional area must equal the volume that comes out of the second cross sectional area.

P1 + ρgy1 + (1/2)ρv12 = P2 + ρgy2 + (1/2)ρv22 - Bernoulli's principle as an equation.