# Solids, liquids and gases revision

- Created by: Sophie
- Created on: 15-05-14 18:32

First 437 words of the document:

Solids, Liquids and Gases Summary

Density

Density () = mass (m) / volume (v)

· Density is how much there is in a given volume

For a regular solid

- Find the volume (volume = width x height x depth) in cm3

- Find the mass with top-pan balance AtpointB,thepressure

- Divide the mass by the volume ac4ngonitis1atm+the

pressureduetothewater

For an irregular solid ofheighth.AtpointC,

- Find the volume by measuring how much water it

thepressureisthesame

displaces in a measuring cylinder

aspointBastheyarethe

- Find the mass with top-pan balance

samedepth.

- Divide the mass by the volume

For a liquid

- Find the mass of the measuring cylinder with a top-pan

balance

- Find the mass of the measuring cylinder and 10cm3 of liquid

- Subtract mass of measuring cylinder to find mass of liquid alone

- Divide the mass by the volume

For a

gas

-Find mass of round-bottomed flask with gas using top-pan balance

-Remove gas from flask with vacuum pump (for 30 seconds)

-Fasten clamp to make sure no air gets in

-Measure mass of empty round-bottomed flask and subtract this from previous reading

-Place end of rubber tubing in water then remove clamp. Allow flask to fill

-Measure volume of water with a measuring cylinder (this is the volume of gas that was

measured)

- Divide the mass by the volume

Pressure

Pressure (p) = Force (F) / Area (A)

· 1 Pascal (Pa) = 1 N/m2

· Solid objects exert downwards pressure upon where they stand.

· The smaller the surface area, the greater the pressure

· In stationary liquids and gases, pressure at any point acts equally in all directions

· Pressure increases with the depth of the gas or liquid (as it has the mass of the liquid/gas on

top of it, which makes it heavier, and so a greater pressure)

· A difference in pressure between two places in a fluid will result in a flow of the fluid from the

place at higher pressure to the place of lower pressure

· Liquids cannot be compressed, so pressure is transmitted through them

· If air gets into hydraulic brakes it is a problem as it can be compressed, so the pressure

wouldn't be transferred

Pressure and Depth

Pressure difference (p) = Height (m) x density (kg/m3) x Gravitational field strength* (N/Kg)

*On Earth, this is 10N/Kg

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