Archimedes Principle

Pressure in Fluids

• Gases and liquids exert pressure on surfaces because of the constant bombardment by their molecules
• Pressure exerted by the atmosphere of the Earth varies with altitude
• At sea level, pressure is about 101kPa
• At the summit of Ben Nevis, pressure is 87kPa

Liquids

• Pressure exerted by a vertical column of any liquid from its weight can be calculated using p=hpg
• h is the height of the liquid, p is the density of the liquid, g is the acceleration of freefall (9.81ms-2)
• p is directly proportional to h, so it shows that pressure increases with depth
• The denser the liquid, the more pressure is exerted

Upthrust

• Upthrust is due to pressure differences
• Take the cross-sectional area of a block of wood to be A and x…