# 9.1 Density and Pressure

##### Chad's General Physics Master Course

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## Density and Pressure

DENSITY AND PRESSURE
Density ρ = m / V          SI Unit: kg/m3
Specific Gravity specific gravity = ρ / ρwater           ρwater = 1000 kg/m3
Pressure P = F / A           SI Unit: Pa = N / m2          1atm = 101,325Pa
Hydrostatic Pressure
(aka Gauge Pressure)
P = ρgh          h = depth
Every 10m depth in H2O = 100,000Pa ~ 1atm
Absolute Pressure P = P0 + ρgh          P0 = atmospheric pressure

1atm = 101,325Pa = 101.325kPa = 760mmHg = 760torr

## Manometers and Barometers

MANOMETERS & BAROMETERS
Manometers Pgas = P0 + ρgh          P0 = atmospheric pressure
Barometers P = ρgh                       P0 = atmospheric pressure

## Pascals's Principle & The Hydraulic Jack

PASCAL’S PRINCIPLE & THE HYDRAULIC JACK
Pascal’s
Principle
The pressure in and enclosed fluid is everywhere the same

P1 = P2

F1 / A1 = F2 / A2
Hydraulic Jack A1 d1 = A2 d2