P2 Kinetic Theory

Note by ShreyaDas, updated more than 1 year ago
Created by ShreyaDas about 7 years ago


IGCSE Physics (P2 Kinetic Theory) Note on P2 Kinetic Theory, created by ShreyaDas on 04/03/2014.

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more temperature =- more kinetic energy- more speed- more vibration- more separation - more potential energykinetic = movement

keep heating a liquid = turns into gas once they escape the other molecules completely


absolute 0 = -273C0K (kelvin)

Liquids and solids are incompressible but gases are easily compressed -- molecules in a gas are spread out

Change of state happens where the temperature seems like it isn't changing -- energy being used for change in statetake longer in L-->G because more separation is neeed

Evaporation occurs when a molecule on the surface has enough energy to escape from the liquid- evaporating molecule has enough energy to break free from the attractive forces between the liquid molecules

when temperature increases the rate of evaporation increases as more molecules move faster and there is more kinteic energy to escape the liquid


they escape by overcoming the forces of attraction 

When you put alcohol of room temperature is spread on your arm it feels cold = takes heat energy from your arm to evaporate

Gas pressure is caused by molecules htting the sides of their container- equal numbers of molecules moving in all directions = pressure is the same in all directionsWhen the molecules hit the sides of the container, they rebound and cause a force


Speed increase = pressure increasebecause:- molecules hit the walls more frequently- more force


Less volume = - same speed- more pressure because it hits the walls more frequently (less space)

Same pressure, more speed = more volume


pressure increase = volume decrease- inversely proportional

Boyle's Law: P1 V1 = P2 V2Pressure of a gas is inversely proportional to the volume provided that the temperature remains constant

when matter is heated -- molecules move faster with more force

matter expandsvolume increases

gases expand the mostliquids nextthen solids 


uses of thermal expansion: thermometersbio-metallic strips in fire alarmslids of jars

Pressure Particles in fluids are constantly moving in a random motion. When they collide with each other, they exert a pressure on the walls of the container.Atmospheric Pressure:The value of atmospheric pressure is 100 kPa (kilo Pascal). The atmospheric pressure is equal to the internal pressure of an object.If the atmospheric pressure is greater than the internal pressure, then the object will collapse as there is less pressure inside to support its shape.Units:Measured in either N/m2 or Pascals (Pa) . 1Pa = 1N/m2

Solids, Liquids and Gases

Kinetic Theory



Thermal Expansion

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