Density and Pressure

equation for density

density = mass/volume

equation for pressure

pressure = force/area

equation for pressure difference

pressure difference =

height x density x gravitational field strength

density

• density is the mass per unit volume

• density tells us how tightly the particles are packed together.

• measured in kg/m3 or cm/m3

describe an experiment to measure the density of an irregular solid

1. fill water into a displacement can until it is overflowing.

2. wait for water to drip out of displacement can spout.

3. weigh the object using scales

4. pace the object in displacement

5. catch the drips from the spout in a measuring cylinder.

6. calculate density of the object:

   density = mass/volume (of water caught in cylinder

pressure

pressure is a measure of how spread out/concentrated a force is.

(pressure is ‘force per unit area’)

Pressure in liquids and gases…

• pressure acts in all directions

• pressure increases with depth

• in gases and liquids at rest, the pressure at any point acts equally in all directions.

the same force applied over a larger area…

creates a lower pressure