Test

Seite 1

Units

degrees Celsius

°C

Temperature

kelvin

K

SI unit of

temperature, starts at absolute zero, is found with °C + 273.15 - or absolute

zero

joule

J

SI unit of energy,

equal to energy transferred to object when a force of 1 newton acts on that

object in the direction of its motion through a distance of one metre (1

newton metre)

kilogram

kg

SI unit of mass

kilogram/metre3

kg/m3

SI unit of density

metre

m

SI unit of

distance

metre2

m2

SI unit of area

metre3

m3

SI unit of volume

metre/second

m/s

SI unit of speed

metre/second2

m/s2

SI unit of

acceleration

newton

N

Si unit of force,

equivalent to a force that would give a mass of one kilogram an acceleration

of one metre/second2

pascal

Pa

SI unit of

pressure, equivalent of a force on an area of one newton per metre2

Density and Pressure

5.2:

Density is the

relationship between the mass of a substance and how much space it takes up

5.4:

where:

p is the unit of

pressure in pascals. One pascal is 1 N/m2

F is the unit of force in

newtons

A is the unit of area

in m2

Pressure is force on an area

Pressure doesn't depend on the shape but the depth of the

container!

Reducing the volume

of the container will cause more frequent collisions and higher pressure

5.5: The pressure at

a point in a gas or liquid which is at rest acts equally in all directions

5.6:

Change of State

5.7

Solids

Properties

Why they are like this

They have a fixed

shape and cannot flow

The particles

cannot move from place to place

They cannot be

compressed or squashed

The particles are

close together and have no space to move into

Liquids

Properties

Why they are like this

They flow and take

the shape of their container

The particles are

free to move around each other

They cannot be

compressed or squashed

The particles are

close together and have no space to move into

Gases

Properties

Why they are like this

They flow and

completely fill their container

The particles can

move quickly in all directions

They can be

compressed or squashed

The particles are

far apart and have space to move into

From

<http://www.bbc.co.uk/education/guides/zgr2pv4/revision>

5.9: Brownian motion

is the random movement if particles in a fluid caused by their collisions. It

doesn’t work in a vacuum and needs particles of varying sizes.

5.10 Their random

movement hits against the wall, causing a force and thus pressure.

5.11 Absolute zero

is the temperature at which no particle can move slower. (273.15°)

5.12 Kelvins start at absolute zero (0K). It is

just Celsius minus 273.15 (also absolute 0)

5.13 Increase in

temperature results in an increase in the average kinetic energy of its

molecules.

5.14 The Kelvin

temperature of the gas is proportional to the average kinetic energy and

pressure of its molecules.

5.15

Imagine a gas is trapped inside a

container which has a fixed size (its volume cannot change).

If the gas is heated the

particles will gain kinetic energy which will make them move faster. This means

they will collide with the walls more frequently.

This causes the force on the

walls of the container to increase and so the pressure increases.

If the temperature of the gas is

measured on the kelvin scale we find that the pressure is proportional to the

temperature.

5.16

From this we can derive the

equation

Where:

is the starting pressure

is the starting temperature

is the finishing pressure

is the finishing temperature

(This equation is true as long as

the volume and mass of the gas are constant.)

5.17

From

<https://en.wikipedia.org/wiki/Boyle%27s_law>

This

is Boyles Law

The equation states

that product of pressure and volume is a constant for

a given mass of confined gas as long as the temperature is constant.

Ideal gas is a gas that obeys Boyles Law exactly. Real gases come close to this

pointy if they have a low density, a temperature well above their liquefying

point, not full of water vapour and no attractions between its molecules.