Physics 2a + 2b

James Squibb
Mind Map by , created over 5 years ago

AQA Physics 2a Mind Map

James Squibb
Created by James Squibb over 5 years ago
P2.6 Nuclear Fission And Nuclear Fusion
P2.4 Using Mains Electricity Safely And The Power Of Electrical Appliances
P2.3 Currents In Electrical Circuits
Chemistry (C1)
Phobae-Cat Doobi
salesforce Developer 1
P2a revision (part 1)
P2a (part 2)
P2.1 Forces And Their Effects
Alex Maraio
Physics P2
Physics 2a + 2b
1 Velocity and Distance-Time Graphs
1.1 Velocity and Speed
1.1.1 Speed How fast you are going e.g. 30mph
1.1.2 Velocity How fast you are going in a direction e.g. 30mph North
1.2 Distance-Time Graph
1.2.1 Important Notes Gradient=Speed Flat=Stationary Straight up or down=travelling at a steady speed Steeper=Faster Downhill=back to starting point Curves=Acceleration or Deceleration Steepening curve=Speeding up Levelling off curve=slowing down
1.2.2 Calculating speed Speed = Gradient = Vertical/Horizontal = 500/30 = 16.7m/s
2 Acceleration and Velocity-Time Graphs
2.1 Acceleration
2.1.1 it is how quickly your velocity is changing
2.2 Velocity-Time Graphs
2.2.1 Flat sections= Steady Speed
2.2.2 Steeper=More de/acceleration
3 Wieght, Mass and Gravity
3.1 Gravity
3.1.1 The force that pulls masses together
3.1.2 Only noticeable when the masses are really really big
3.2 Weight
3.2.1 The force of gravity pulling it towards the earth
3.3 Mass
3.3.1 Mass is the amount of stuff
4 Resultant Forces
4.1 The resultant force is the overall force on a point or object
4.2 If you have a number of forces acting on a point or object you can replace them with a single force
4.2.1 As long as they are parallel and act in the same or opposite direction you can swap it for one force by just addind or subtracting them The overall force you get is the resulting force
5 Forces and Accceleration
5.1 If the resultant force of a stationary object is 0, then the object will remain stationary
5.2 For a object to remain at a constant speed then the resultant force must be 0
5.3 If there is a non-zero resultant force then the object will be accelerating or decelerating
5.4 Formula
5.4.1 F = ma or a = F/m m = mass kg a = acceleration m/s2 F = the resultant force N
5.5 When two objects interact, the forces they exert on each other are equal and opposite
6 Frictional Force and Terminal Velocity
6.1 You get friction between two surfaces in contact or when an object passes through liquid
6.2 Friction slows things down
6.3 Drag increases as speed increases
6.4 the faster the object moves at the more friction it has resisting it
6.5 Objects falling through fluids reach a terminal velocity
6.6 when an object falls it will accelerate until the frictional force is equal to the accelerating force so it will fall at a steady speed
7 Stopping Distances
7.1 Stopping Distance = thinking distance + Braking Distance
7.2 Thinking Distance
7.2.1 2 Factors Speed Dopiness Drugs Alcohol tiredness
7.3 Braking Distance
7.3.1 4 Factors Speed Quality of Brakes Tires + Road surface Tread Depth Water Oil Spillages Grip Road Surface Weather Tyres
8 Work and Potential Energy
8.1 When a force moves an object through a distance, Energy is transferred and work done.
8.2 Gravitational potential energy
8.2.1 Gravitational Potential Energy = mass x g x height
8.2.2 Gravitational potential energy is the energy that an object has because of its vertical position in a gravitational field
9 Kinetic Energy
9.1 K E = 1/2 x mass x speed2
9.2 Anything that is moving has K E
9.3 Due to the law of the conservation of energy
9.3.1 When a car is moving the kinetic energy is transferred to heat energy when breaking Kinetic energy transferred = work done by brakes 1/2 x mass x speed2 = F x D
10 Forces and Elasticity
10.1 Work done to an elastic object is stored as elastic potential energy
10.2 Extension of an elastic object is directly proportional to force.
10.2.1 This stops working when the force is great enough There is a limit to the amount of force you can apply to an object for the extension to keep on increasing proportionally
10.3 F = k x E
11 Power
11.1 Power is the rate of doing work - I.E. How much per second
11.2 P = Work done / Time taken
11.3 Measured in Watts
11.3.1 1 watt = 1 joule transferred per min
12 Momentum and Collisions
12.1 Momentum = mass x Velocity
12.2 conservation of momentum
12.2.1 Momentum before = Momentum After
12.3 Forces cause changes in momentum
12.4 The larger the force the faster the change in momentum
12.5 Cars are designed to slow down slower in a crash so that the forces are smaller on the human body.
13 Car Design and Safety
13.1 Brakes
13.1.1 Brakes do work against the k e of the car.
13.1.2 Regenerative brakes convert the heat energy from the brakes to electrical energy which is stored chemical energy
13.2 Cars are designed to convert kinetic energy safely in a crash
13.2.1 Crumple Zones Car body changes shape at front and rear in a crash
13.2.2 Side Impact bars Metal tubes in side of car They help to divert the energy away from the passengers towards other parts of the car.
13.2.3 Seat Belts Around passengers body stretch slightly to increase time for passenger to stop.
13.2.4 Air Bags stop you from hitting hard surfaces
13.2.5 Power Ratings the higher the engine power the higher the power rating
14 Static Electricity
14.1 The build up of static electricity is caused by friction
14.2 When certain insulating materials are rubbed together - charged electrons will be rubbed off and dumped on the other
14.3 It is ONLY the electrons that move -
14.4 Like charges repel, Opposite charges attract.
14.5 Charges can move easily through conductors - metals
15 Current and Potential Difference
15.1 P.D = the driving forces that pushes the current round . Volts
15.2 the greater the resistance across a component, the smaller the current that flows.
15.3 Total charge through a circuit depends on current and time
15.3.1 Current = charge/Time
15.4 P.D is the Work Done per unit charge
15.4.1 P.D = Work Done / Charge
16 Circuits - The Basics
16.1 Ammeter
16.1.1 Measures current
16.1.2 Must be in Series
16.2 Voltmeter
16.2.1 Measures P.D - Voltage
16.2.2 Must be in parallel
17 Resistance
17.1 Resistance increases on tempreture
17.2 The longer the wire the more resistance
17.3 The smaller the diameter of the wire the more resistance
17.4 P.D = Current x Resistance
18 Circuit Devices
18.1 Diodes
18.1.1 1 way
18.2 LED
18.2.1 Emits light when a current flows through in a forward direction
18.3 LDR
18.3.1 More light less resistance
18.4 Thermistor
18.4.1 As temp increases resistance decreases
19 Series Circuits
19.1 All connected in a line
19.2 P.D is shared
19.3 Current is the same everywhere
19.4 Resistance adds up
20 Parralel Circuits
20.1 Separately connected to the supply
20.2 P.D is the same across all components
20.3 Current is shared between branches
21 Series and parallel circuits
21.1 Series Circuit - Example
21.1.1 Christmas Trees lights
21.2 Parallel Circuit - Example
21.2.1 Cars electrics
22 Mains electricity
22.1 Mains supply is AC battery supply is DC
22.2 The UK mains supply is approximately 230 volts
22.3 It is a Alternating current, which means it is constantly changing direction
22.4 Electricity supplies can be shown on a oscilloscope
22.5 on a oscilloscope a AC current will be a wave and DC will be a straight line
22.6 Th e vertical height of AC is the input voltage
22.7 On DC, the distance from the centre line to the trace is the voltage
23 Electricity in the home
23.1 Hazards
23.1.1 Long Cables
23.1.2 Frayed Cables
23.1.3 Cables in contact with something hot or wet
23.1.4 Water near sockets Socket overloading Lighting sockets without bulbs
23.1.5 Shoving things into sockets
23.1.6 Damaged plugs Appliances without covers on
23.2 Most cables have three separate wires
23.2.1 The brown LIVE WIRE in a mains supply alternates between the high +VE and -VE VOltage The blue NEUTRAL WIRE is always at OV. Electricity normally flows in and out through the live and neutral wires only. The green and yellow wire is the EARTH WIRE. it is for protecting the wiring and for safety It works with fuse to prevent fires and shocks
23.3 Learn the safety features
23.3.1 The right coloured wire is connected to the right pin
23.3.2 No bare wires showing inside the plug
23.3.3 Cable Grip
24 Fuses and Earthing
24.1 Earthing and fuses prevent electrical overloads
24.2 If there is a fault in the circuit, because of the earth it will connect and make the fuse break because the current is too great. This isolates the whole appliance
24.3 Insulating Materials make appliances "Double Insulated"
24.3.1 Double insulated appliances don't need a earth wire because there is nothing to earth
24.4 Circuit Breakers have some advantages over fuses
24.4.1 They are the same as fuses but they open a switch instead of break / melt
24.4.2 They also can be reset by a switch which is more convenient than fuses and cheaper
25 Energy and Power in circuits
25.1 Energy is transferred from cells and other sources
25.1.1 Anything which supplies electricity is also supplying energy
25.1.2 Kinetic energy = motors
25.1.3 Light energy = lamp
25.1.4 Heat energy = Kettles
25.1.5 Sound energy = speakers
25.2 All resistors produce heat when a current flows through them.
25.2.1 When an electric current flows through anything with electrical resistance then electrical energy is converted into heat energy
25.2.2 The more current the more heat
25.2.3 The more voltage means more heating
25.3 If an appliance is efficient it wastes less energy
25.3.1 Appliances that are energy efficient transfer more of their total electrical energy output to useful energy
25.4 Power Ratings of appliances
25.4.1 The total energy transferred by an appliance depends on how long the appliance is on and it's power rating. The power of an appliance is the energy that it uses per second
25.4.2 Energy Transferred = Power rating x Time
26 Power and energy change
26.1 Electrical Power and Fuse Ratings
26.1.1 Power = current x potential difference (voltage) Most electrical goods show their power rating and voltage rating. To work out the size of the fuse needed, you need to work out the current that the item will normally use.
26.2 The Potential Difference is the energy transferred per charge passed
26.2.1 when charge (Q) goes through a change in potential difference (V), then energy(E) is transferred. Energy is supplied to the charge at the power source to 'raise' it through a potential. The charge gives this energy when it 'falls' through any potential drop in components elsewhere in the circuit. Energy transformed = charge x potential difference The bigger the change in PD the more energy is transferred for a given amount of charge passing through a circuit
27 The Atomic structure - and Rutherford
27.1 In 1804, John Dalton agreed with democritus that matter was made up of tiny spheres (atoms) that couldnt be broken up
27.1.1 100 years later J J Thomson discovered that electrons could be removed from atoms In 1909, Rutherford and Marsden tried firing a beam of alpha particles at a thin sheet of gold foil They expected that the positively charged alpha particles would be slightly deflected by the electrons in the plum pudding model. However, most of the particles went straight through, but the odd one came straight back at them. They realised that most of the mass was in the + charged nucleus
27.2 Rutherford and Marsden came up with the nuclear model
28 Atoms and Ionising Radiation
28.1 Isotopes are different forms of the same element
28.1.1 An isotope has the same amount of protons and electrons, however has a different number of neutrons
28.2 Radioactiviiy is a totally random process
28.2.1 Radioactive substances give out radiation from the nuclei of their atoms, whatever is done to them. Radioactive substances spit out one or more of the three types of radiation - alpha, beta and gamma
28.3 Background radiation comes from many sources
28.3.1 Radioactivity of naturally occurring unstable isotopes which are all around us Radiation due to man made sources - Nuclear weapons tests, nuclear accidents, dumped nuclear waste. Radiation from space - cosmic rays
28.4 Atoms and Ionising Radiation
28.4.1 Alpha particles they are the same as a helium nucleus, and they are big and heavy and slow moving. Therefore they don't penetrate very far into materials and are stopped quickly, even when travelling through air. Because of their size they are strongly ionising. Which means they bash into a lot of atoms ans knock electrons off them before they slow down, which creates lots of ions.
28.4.2 Beta particles Beta particles are electrons. They move quite fast and they are quite small (they're electrons). They penetrate moderately into materials before colliding, have a long range in air, and are moderately ionising too. For every Beta particle emitted, a neutron turns to a proton in the nucleus. A B-particle is an electron, with virtually no mass and a charge of -1
28.4.3 Gamma rays Gamma Rays, are very short wavelength, EM Waves. They are the opposite of alpha particles in a way. They penetrate far into materials without being stopped and pass straight through air. This means they are weekly ionising because they tend to pass through rather than collide with atoms. Eventually they hit something and do damage. Gamma rays have no mass and no charge.
28.4.4 Radiation Dose The damage caused by radiation depends on the radiation dose Enter text here Radiation dose depends on the type and the amount of radiation. Radiation Dose depends on location and occupation Certain underground rocks (e.g. granite) can cause higher levels at the surface, especially if radioactive radon gas is released and it can get trapped in people's houses. Nuclear Industry workers and uranium miners are typically exposed to 10 times more radiation than normal. They have to wear hazmat suits to stop them from touching or inhaling radioactive substances. They monitor their doses with badges and check ups. Radiographers work in hospitals using ionising radtion and so have a higher risk of radiation exposure. They wear lead aprons and stand behind lead screens to protect them from prolonged exposure to radiation. At high altitudes the background radiation is higher because your closer to cosmic rays. Also underground for miners because they're surrounded by rocks.
29 Half-Life
29.1 The radioactivity of a sample always decreases over time
29.2 As a radioactive sample decays it loses more atoms, therefore as it decays it will lose in mass and will emit less radiation
29.3 The half life of a substance is how long it takes for half of the starting substance to decay.
29.3.1 for example a substance with a half life of 4 years and a starting mass of 10kg will decay to 500g after 4 years.
29.4 Here is a Half life graph ===>
30 Uses of radiation
30.1 Smoke detectors - use alpha radiation
30.1.1 Tracers in Medicine - Always short half life Beta or Gamma emitters
30.2 Radiotherapy - the treatment of cancer using gamma rays
30.2.1 Sterilisation of food and surgical instruments using gamma rays
31 Radioactivity safety
31.1 Radiation harms living cells
31.1.1 Radiation will enter living cells and collide with the molecules These collisions cause ionisation, which damages or destroys the cells Lower doses tend to cause minor damage without killing the cell. This can give rise to mutant cells which divide uncontrollably, this is called cancer. Higher doses kill cells which causes radiation sickness, if a lot of cells get hit all at once The severity depends on the exposure, energy and penetration and type of radiation. Outside the body Beta and Gamma radiation is the most dangerous Inside the body alpha radiation is the most dangerous because it does the most ionising
31.2 Safety Precautions
31.2.1 1) use for the shortest time possible
31.2.2 2) Never allow skin contact with the source
31.2.3 3) Hold it at arms length, to reduce amount of radiation particles that hit you
31.2.4 4) Point it away from you
31.2.5 5) Use lead to store it because it absorbs the radiation
32 Nuclear Fission and Fusion
32.1 Nuclear Fission
32.1.1 Nuclear Power stations use nuclear reactors to produce energy inside, a controlled chain reaction takes place which atomic nuclei split up and release heat energy The heat, heats water which creates steam which turns a turbine, which generates electricity
32.2 Nuclear Fussion
32.2.1 It is the joining of small atomic nuclei. Two light nuclei(hydrogen) can join to make a nucleus - this is called fusion. Fusion creates even more energy than fission. So people are trying to make fusion reactors, and there isn't much waste left behind and there is plenty of hydrogen. The only problem is that it can only happen at really high temperatures - 10 000 000'c For this you need a extremely strong magnetic field, there are a few experimental reactors around but non of them are generating electricity yet.
32.3 The chain reactions
32.3.1 For fission, a slow moving neutron must be absorbed into a uranium or plutonium nucleus. This extra neutron makes it unstable, causing it to split. Each time a nucleus splits up it spits out two or three more neutrons, which hit another nucleus causing another split, therefore the chain reaction continues.
32.3.2 Nuclear fission gives out a lot of energy. Nuclear processes give out a lot more energy than chemical processes do e.g. Nukes.
33 The Life Cycle of stars
33.1 1) Protostar - clouds of dust and gas pulled together into spirals by gravity
33.1.1 2) gravitational energy is converted to heat until nuclear fusion happens, this gives out massive amounts of heat and light. A star is born 3) Main Sequence Star - The star immediately enters a long stable period. The heat energy creates outward pressure which balances gravity pulling everything inwards. This energy output maintains for millions of years due to the massive amounts of hydrogen, this period lasts for several billions years 4) Small Star/Red Giant - Eventually the hydrogen begins to run out and heavier elements such as iron are made through the nuclear fusion of hydrogen. As it's a small star it swells into a red giant. 5) The star then becomes unstable and ejects it's outer layer of dust and gas as a planetary Nebula 6)This leaves behind a hot dense solid core - a white dwarf, which cools to become a black dwarf and eventually disappears 4)Large star/Super Red Giant - Eventually the hydrogen begins to run out and heavier elements such as iron are made through the nuclear fusion of hydrogen. As it's a large star it swells into a Super Red Giant. 5)The star starts to glow brightly again, as they undergo more fusion, they expand and contract several times, forming heavy elements such as iron. Finally they explode to create a Super Nova, forming elements heavier than iron and ejecting them into the universe to form other planets and stars. 6) The remainders of the super nova is a very dense core called a neutron star. If the star is big enough it will become a black hole.