Distance Distance-Time Graphs Gradient = Speed Flat sections
are stationary Straight = steady speed Curves= acceleration or
deceleration
Slide 3
Velocity and Acceleration Acceleration is how quickly velocity
is changing Acceleration=Change in Velocity/Time Taken
Velocity-Time Graphs Gradient = Acceleration Flat sections = steady
speed Area under the graph represents distance Curve is change in
acceleration
Slide 4
Weight MASS is the stuff inside, whereas WEIGHT is the force
due to gravity Weight = Mass x Gravitational Field Strength Earths
GFS is 10N/Kg
Slide 5
Resultant Forces It is the overall FORCE The overall effect of
forces which will decide the motion of an object If two forces are
acting in the same direction, the resultant force is the sum of
those two If two forces are acting along the same line, then the
resultant force is found by subtracting them
Slide 6
Driving force =1000N Pushing Force =600N Resultant Force =1600N
Driving force =1000N Friction =600N Resultant Force =400N
Slide 7
Acceleration If the resultant force in 0 the object is
stationary It there is no resultant force on a moving object, then
it will carry on moving with constant velocity If there is an
resultant force, then the object will accelerate in the direction
of the force That is until the force equal out again
Slide 8
Force = Mass x Acceleration Or Acceleration = Force / Mass When
two object interact, the forces they put (exert) upon each other
are equal and opposite This is called a reaction force, so if you
push against something it will push back against you with equal
force
Slide 9
Friction It acts against movement If you travel at a steady
speed, the driving force needs to equal the frictional force
Streamlining reduces drag or air resistance Drag increases as speed
increases, as you accelerate you hit more air particles with more
force. This created more drag
Slide 10
Terminal Velocity When an object first falls, gravity (weight)
has more force than frictional forces This causes the object to
accelerate downwards As the speed increases, so does the drag This
reduces the acceleration Weight can not get any bigger, so you
reach terminal velocity (fall at a steady speed)
Slide 11
Stopping Distance Thinking Distance Faster you are going =
Further you will go Your Reactions- Tiredness, drugs, alcohol, bad
visibility and distractions Braking Distance Faster you are going =
Further you will go The Car- the condition of Tyres and condition
of Brakes The Road- road surface and weather condition
Slide 12
30 mph 50 mph 70 mph 9m 15m 21m 14m 38m 75m So this shows that
thinking distance is directionally proportional but braking
distance is squarely proportional Thinking Braking Distance
Distance Stopping Dis. = Thinking Dis. + Braking Dis.
Slide 13
Work Done To move an object energy has to be transferred The
energy can be used usefully i.e. To move something or wastefully
i.e. Friction Work Done= Force x Distance Moved
Slide 14
Gravitational Potential Energy When an object is lifted
vertically work is done against the force of gravity. This is
transferred into gravitational potential energy (GPE) GPE= Mass x
Height x GFS (gravitational field strength) The Earth has a GFS of
10N/Kg
Slide 15
Kinetic Energy Any thing that moves has kinetic energy Kinetic
Energy = Mass x Speed Moving car has lots of KE so to slow it down
energy is lost i.e. Heat energy Work done = KE F x d = mv Falling
objects have the potential energy lost and they gain kinetic
energy
Slide 16
Elasticity Apply a force = Stretch the Object Work done is
stored as ELASTIC POTENTIAL ENERGY Then its goes back to its
original shape releasing the energy as KINETIC ENERGY
Slide 17
Extension of Spring is DIRECTIONALLY PROPORTIONAL to the force
applied Force = K (spring constant) x energy There is a limit to a
springs elasticity, it is normal until it reaches its maximum force
Past this point the spring will not return to its original
shape
Slide 18
Power It is the rate of doing work Power = Work Done / Time
Taken Measured in Watts, which means 1 Watt is 1 joule of energy
transferred every second
Slide 19
Momentum Its a property of a moving object Momentum = Mass x
Velocity Also P before = P after Momentum is a vector, so has
direction When a force acts upon an object it changes its momentum
The bigger the force the faster the change of momentum
Slide 20
Car Safety Brakes transform the kinetic energy of the car into
thermal energy on the road Regenerative brakes dont transform into
heat the transform into electrical energy Big change in Momentum in
a short time = MASSIVE
Slide 21
END OF FIRST HALF
Slide 22
Static Electricity It is created when two object rub against
each other and either lose or gain electrons Like charges repel, so
if hair had been charged then the hair would separate because their
like charges repel each other However these charges can be easily
lost through a conductor
Slide 23
Current and Voltage Current is the rate of flow of charge
Current= Charge / Time The Potential Difference is the work done
per coulomb of charge Voltage = Work Done / Charge
Slide 24
Circuits
Slide 25
Resistance Current through a resistor (at constant temp.) is
directionally proportional to Voltage The higher the resistance the
higher the potential difference However in a normal filament lamp
the temperature of the filament increases this causes the curve
This is a Diode. The current will only flow in one direction. The
diode has a very high resistance in the opposite direction
Slide 26
Series All or nothing, if one component breaks ao does the
circuit Potential difference is shared out, so in 23 fairy-lights
on the mains electricity they all have a voltage of 10V Current is
the same everywhere And the Resistance builds/adds up, 5 bulbs with
10 so the circuit has 50
Slide 27
Parallel Things can be switched off separately Voltage is the
same across all components However current is shared between each
branch. The current going in is the same as going out, but the
components have different currents going across them
Slide 28
Mains Electricity Supplied in AC Has 230V And has frequency of
50Hz It can be shown on an oscilloscope
Slide 29
Electricity in the Home Hazards: Long Cables; Frayed cables;
damaged plugs; too many plugs in 1 socket; water near sockets The
wires: Live wire carries the alternating current; Neutral has 0V
and Earth is attached to metal casing
Slide 30
BLUE E F T BROWN I G H T
Slide 31
Fuses and Earthing Fault in the LIVE WIRE causes it to touch
the metal case This causes a larger current to flow through the
circuit This surge cause the FUSE to MELT This cuts of the live
supply and breaks the circuit, THUS saving the appliance and the
user
Slide 32
Live wire touches the metal casing Big Surge of Electricity to
earth Fault in the Live Wire The Fuse melts/blowsThe appliance is
SAFE
Slide 33
Energy and Power All resistors produce heat when a current
flows through them. The more current the more heat To be energy
efficient they have to transfer more of their total electrical
energy to a useful source Energy Transferred= Power Rating x
Time
Slide 34
Atomic Structure- Rutherford In 1909 Rutherford fired alpha
particles at gold foil to discover more about particles He found
most went straight through, this shows particles are mostly empty
space Some came straight back, the shows that most of the mass is
concentration in a central nucleus Some were deflected, this shows
the nucleus is positive and there must be negative electrons not in
the nucleus
Slide 35
Radiation Isotopes are atoms of the same element but are
slightly different, they have the same number of protons but
different numbers of neutrons Radioactivity is entirely random, it
comes from an unstable and decaying nuclei. This emits alpha, beta
or gamma radiation Background radiation comes from: naturally
unstable isotopes like rocks and food; space like cosmic rays;
Man-made places like weapons and medicine and power-stations
Slide 36
Types of Radiation Alpha radiation is a helium nucleus, so two
protons and two neutrons. Cant penetrate much but because of its
size its strongly ionising (bash into atoms and knock electrons off
of them) Beta radiation is an electron which is emitted when a
neutron turns into a proton. Can go through some things and is
mildly ionising Gamma radiation is an ray. This penetrates
everything but is weakly ionising.
Slide 37
Radiation Safety Radiation damage depend on the type of
radiation and how long you were exposed Alpha particles are
deflected slightly by magnetic field but beta particles are
extremely deflected by the magnetic field Granite release radon gas
which can be trapped in peoples houses Nuclear industry workers
wear protective clothing and face masks and have radiation badges
Radiographers work behind lead screens and wear lead aprons
Slide 38
Half-Life Half life is the AVERAGE TIME it takes for the NUMBER
OF NUCLEI in a radioactive isotope to HALVE Radioactivity never
stops, there will always be some activity, so its hard to measure
Short half life means lots of nuclei decay quickly, activity falls
quickly
Slide 39
-1 Half Life-
Slide 40
Uses of Radiation Smoke detectors- alpha particles make and
circuit and smoke breaks the circuit, making the alarm go off
Sterilisation- Gamma rays are used to kill bacteria on food or
medical equipment, without harming them Radiotherapy- gamma is
fired at a cancer to kill all of those cells, but damage is done
Tracers- beta or gamma sources are put into someone and an external
detector says where most of the radiation is
Slide 41
Damage of Radioactivity Large amounts of radiation kill cells
and leave you with radiation sickness, but nothing else Small
amounts cause minor damage to cells without killing them. They then
mutant and divide uncontrollably, this is a cancer Alpha is very
harmful inside the body because it damages a very localised area
Beta and gamma are dangerous outside the body because they can
penetrate the skin
Slide 42
Nuclear Fission This is what happens in nuclear power stations
and nuclear bombs An Neutron had to be absorbed by an unstable
nuclei This creates two new smaller nuclei and releases more
neutron, this makes a chain reaction This gives out a lot of
energy
Slide 43
Nuclear Fusion This is where two small nuclei join to create a
larger nucleus and energy Fusion doesnt leave a lot of radioactive
waste and there is a bounty of fuel (hydrogen) It can only happen
at really high temperatures You need at strong magnetic force to
hold the pressure and heat 2121 HH 1111 + 3232 He+ ENERGY
Slide 44
Life Cycle of Stars Nebula- The nursery for Stars. Clouds of
Dust and gas start to form. Gravity makes it spiral and form a
Protostar Protostar- Gravity is turned into heat. The temp is then
high enough for nucleur fusion to start. This gives out light, star
Main Sequence star- long stable period where outward pressure is
equal to the force of gravity (the sun) but this cant last forever
Red Giant- hydrogen has run out and it was a small star Red
SuperGiant- Hydrogen has run out but it was a big star OR
Slide 45
Red Giant Red Giant- small star make this. It is unstable so
ejects its outer layer of dust and gas. White Dwarf- This is whats
left after the red giant. It is a hot solid, dense core. When it
cools down it becomes a Black Dwarf Planetary Nebula- This is the
outer layer of duct and gas.
Slide 46
Red SuperGiant Red SuperGiant- This is made from large stars.
They glow more brightly because they do more fusion, so they expand
Supernova- This is the explosion of the Red SuperGiant. It forms
elements heavier than iron and spreads them out into the universe
creating new planets and new stars Neutron Star- What is left of
the supernova is a dense core. This is an neutron star OR Black
Hole- If the star is big enough the remains of the supernova will
form a black hole
