# Physics - Section E: Solids, Liquids and Gases

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- Created by: caaseyjoness
- Created on: 04-02-14 21:37

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**Density and Pressure**

**Density**

Denisity is the mass per unit volume of a substance and can be dound using the equation:

Denisity = Mass / Volume

The units for denisty ar kg/m cubed or g/cm cubed

**Measuring dentisty**

- To calulate the mass of a regular object, such as a cuboid, calculate the volume of the object using V=l x w x h. Then find the mass of the object using an electronic balance. Use the formula to calculate density.
- To calulate the mass of an irregular solid, such as a stone, place the object in a displacement can filled with water, with a measuring cylinder graduated in cm under the spout. When the water stops flowing, read the value at the meniscus on the measuring cylinder. Then weigh the object on an electronic balance. Use the forumla to calculate density.

**Pressure**

Pressure is the effect of a force - it tells us how concentrated or spread out a force is.

Pressure = Force / Area

The units for pressure are Pa or N/m squared.

**Devices Used that Rely On Low and High Pressure**

- High pressure - teeth, drswing pins, scissors, chef knife, bolt cutters etc.
- Low pressure - caterpillar…

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