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# Physics P1 AQA

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## Justine rykiel

on 19 January 2015

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#### Transcript of Physics P1 AQA

State of Matter
The changes in matter (solid, liquid and gas) is caused by a change in temperature
Evaporation and Condensation
Rate of evaporation is increased by:
Convection
Convection currents are caused by fluids (gases and liquids) being heated, which changes their density
All objects emit and absorb infrared radiation
Conduction
Occurs mainly in solids
Physics P1a AQA
This shows the infrared radiation given of by us.
Conduction in metals
Metals conduct heat better because they have free electrons
Convection Currents
Black
and mat objects edmit and absorb the most infrared radiation
1.1 &1.2
Infrared makes you feel warm and is transmitted by electromagnetic waves (so they can travel through a vacuum, like the sun's heat)
The hotter an object is the more infrared is being edmitted
( they transfer heat quicker)
1.3
Solids
Fixed positions but can vibrate so it has a fixed shape.
Liquids

Weak bonds between particles so they can move around each other at random, which means that it doesn't have a fixed shape, and can flow.
Gases
The particles move fast and at random whilst moving around each other so it doesn't have a fixed shape.
There are large spaces between the particles so it is less dense the liquid which is less dense then solids
Least kinetic energy
Most kinetic energy
Far apart.
In contact with each other
In contact with each other
1.4
Gains kinetic energy and vibrates more. Thermal energy to kinetic energy
Kinetic energy is passed onto the surrounding particles by them colliding
More energy=more heat
Free electron
The free electrons can move around the particles and pass the kinetic energy to particles which is quicker
Poor conductors are insulators, they usually contain trapped air, air is a poor conductor.
1.5
When a fluid is heated it gains kinetic energy, which causes the spaces between the particles increase
This means that there are less particles per a square cm so the density is decreased
So it rises above the higher density fluid which is then heated like before
This then rises and happens again and again until all the fluid is equally as hot
Heat
Cool air is dragged underneath
1.6
A bigger surface area
A hotter temperature
A draught of air across the surface
Rate of condensation is increased by:
A bigger surface area
Cooler surface area
Evaporation
Particles with the most kinetic energy leave the surface of the liquid
This means that the average amount of kinetic energy is lowered, so the liquid is reduced
Liquids have weak bonds between the particles and are close together. As they are heated it gains more kinetic energy and move apart, breaking the bonds
Transfer energy by design
Some products are designed to transfer energy easily by:
Using good conductors
Are painted dull and black
Have an air flow (not trapping air)
The rate of transfer depends on:
Shape, size, material its made from
Material its in contact with
Temperature difference
1.7
Specific Heat Capacity
E=MxCxO
_
E=Energy J
M=mass Kg
C=specific heat capacity J/Kg C
O=Temperature change C
How much energy it takes to heat 1Kg by 1 degree
_
o
o
1.8
1.9
Heating and Insulating buildings
U-values- it tells us how much energy per a second passes though it
The lower the better it is at insulating
Fiberglass insulating reduces energy transfer by conduction
Cavity wall insulation reduces energy transfer by convection
Double glazing reduces conduction
Energy
2.1&2.2&2.3&2.4
Gravitational potential
Elastic potential
Chemical potential
Kinetic energy
light
Thermal (heat)
Nuclear
Electrical
Stored energy
Energy can not be destroyed or created
Useful energy is the output energy that is used
Useful and wasted energy both end up being transferred into its surroundings
Efficiency is the percentage of output energy that is useful
Efficiency=
Useful energy transferred
Total energy supplied
x100
3.2&3.3&3.4
Power, using energy and cost effectiveness
Power (W)=
Energy (J)
Time taken (sec) for energy to be transferred
Companies measure power in KW and energy in KWh, and to find the cost you times it by the cost per hour.
Cost effectiveness