Physics in a nutshell

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  • Created on: 14-04-13 13:35
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IGCSE Physics in a nutshellquick revision
1. Speed vs time graphs. The area under gives distance travelled and gradient gives
acceleration, (change in speed/time)
2. total stopping distance of a car = thinking distance + braking distance
3. Thinking distance is affected by alcohol/drugs, tiredness, alertness of driver.
4. Braking distance is affected by condition of brakes, grip of road surface, mass of vehicle
and initial speed of vehicle.
5. Newton stated that forces change the speed (or shape or direction) of something. F=ma
6. For something falling Weight = mass × g
7. Drag (air resistance) increases with speed and causes any moving mass to have a
maximum speed when drag is equal to the driving force.
8. A moment is the turning effect of a force pivot: moment = force × perpendicular distance
from pivot
9. Springs and wires obey Hooke's law when stretched as extension is directly proportional to
load applied upto the elastic limit and so a graph of extension against load is a straight line
1. Current is rate of flow of charge in Coulombs per second I=Q/t
2. dc flows in one direction only and ac continually changes direction.
3. Calculate resistance using R= V/I
4. Circuit to measure current and voltage. The shape of a current against voltage graphs can
be used to identify which component the graph is for: metals at constant temperature,
(straight line as current is proportional to voltageOhms law) bulbs (curved graph),
diodes(zero current when voltage is negative).
5. The colour code for domestic wiring is : brown live, blue neutral, yellow green earth. The
fuse is in the live wire. Choose the correct fuse by calculating the usual current from I=P/V
6. Live current = neutral current , even though the neutral is at 0V and the live is at 230V.
These wires are needed to pass current through the appliance but the earth wire is joined to
the metal case and has no current unless there is a fault. It prevents electric shock. An
alternative to earthing is double insulation
7. Appliances that use the heating effect of a current are as irons, kettles, toasters
8. Calculate electrical power from P=IV and electrical energy transferred as E = Ivt
1. Describe a variety of everyday and scientific devices and situations, explaining the fate of
the input energy including their representation by flow diagrams
2. Energy is transferred when work is done. Work done = force × distance moved by the force
3. Kinetic energy = ½ × m v2
4. Gravitational potential energy = mgh
5. Power = rate of doing work. Power = Work done/ time taken
6. Nonrenewables (oil, coal, gas)are being used at a faster than they are being produced so
will run out unless practice changes. They also contribute to global warming by releasing
carbon dioxide and to acid rain by releasing sulphur dioxide. They contain a large amount of
chemical energy per unit mass.
7. Renewables (wind, waves, hydroelectric, tidal, biomass, geothermal) are constantly
supplied with energy from the sun so will continue for as long as the sun shines. They tend
to be less polluting though may destroy habitats. They tend to contain less energy per unit
mass than fossil fuels.

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1. In transverse waves the oscillations are at right angles to the wave eg electromagnetic
waves, water waves, in longitudinal waves the oscillations are parallel to the wave eg sound
and ultrasound
2. Frequency is the number of waves/sec, amplitude is the maximum displacement of a
particle and wavelength is the distance from one wave crest to the next.
3. Frequency = 1/time period
4. Wave speed = frequency x wavelength
5. Waves can be reflected angle of incidence = angle of reflection
6.…read more

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Solids, liquids and gases
1. 1. Describe and draw diagrams to show the motion and bonds between molecules in solids,
liquid and gases
2. Density = mass / volume experiments involving density
3. Pressure = force/area
4. Brownian motion provides evidence for the existence of molecules
5. For a fixed amount of gas at constant temperature pressure x volume remains constant so
P1V1=P2V2 If the pressure is doubled the volume is halved
6.…read more



Hey i would love to know where you got these notes!! need them for other subjects!! **

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