# Archimedes Principle

- Created by: theninjaemu
- Created on: 23-11-16 13:55

View mindmap

- Archimedes Principle
- Pressure in Fluids
- Gases and liquids exert pressure on surfaces due to constant bombardment by their molecules
- Pressure exerted by the Earth varies with altitude
- The pressure at sea level is 101kPa
- At the summit of Ben Nevis, the pressure is 87kPa

- Liquids
- Pressure exerted by a vertical column of any liquid is calculated using P=hpg
- h is the height of the liquid
- p is the desnsity
- g is the acceleration of freefall (9.81ms-2)

- p is directly proportional to h, meaning pressure increases with depth
- The denser the liquid, the more pressure is exerted

- Pressure exerted by a vertical column of any liquid is calculated using P=hpg
- Upthrust
- Upthrust is due to pressure differences
- If the cross sectional area of a block of wood is A and its height is x:
- The force at the top surface is hpgA
- The force at the bottom surface is (h+x)pgA
- the resultant upward force is (h+x)pgA-hpgA
- This is the equation for upthrust

- The volume of the block of fluid displaced is Ax, with a mass of (Ax)p
- Upthrust is equal to the weight of the fluid diplaced
- Archimedes Principle: the upthrust exerted on a body immersed fully or partially in a fluid, is equal to the weight of the fluid that the body displaces
- An object will sink if the upthrust is less than the weight
- For an object to float, the upthrust must be equal to the weight

- Icebergs
- 9/10 of an iceberg is under water
- Densities at 0 degrees C
- Ice = 900kgm-3
- Water = 1000kgm-3

- An ice cube with sides 1m will have a weight of (900x9.81)=8830N
- When it floats, it will displace water of weight 8830N which has a volume of 0.9m3 (8830/1000x9.81)
- The ice cube will sink until it displaces 0.9m3 of water
- This is 9/10 of the volume of the cube

- Pressure in Fluids

## Comments

No comments have yet been made