Presentation on theme: "P2 revision Motion Forces and their effects Kinetic energy Momentum"— Presentation transcript:
1 P2 revision Motion Forces and their effects Kinetic energy Momentum Electrical circuitsMains electricityNuclear physics
2 Graphs of motion are a visual representation of the motion of a body LO: understand how to draw and interpret graphs of motionGraphs of motionGraphs of motion are a visual representation of the motion of a bodyThey can either show the change in displacement or change in velocity of an object
3 P2 1.1 Distance-time graphs How can we tell from a distance-time graph if an object is stationary or moving at constant speed? How do we calculate speed of a body?The slope on a distance-time graph represents speed.Speed (metre/second, m/s) = distance travelled (m)time taken (s)DSt
4 Using distance-time graphs LO: understand how to draw and interpret graphs of motionUsing distance-time graphsHow steep the line is (the gradient) on a distance-time graph tells you the speed that an object is movingThe steeper the line, the faster something is movingSpeed is measured in m/s
5 Calculating the gradient LO: understand how to draw and interpret graphs of motionCalculating the gradientChange in yGradient =Change in x∆yGradient =∆xThe gradient of a distance-time graph represent the speed of an object.
6 P2 1.2/3 Acceleration and Velocity time graphs What is the difference between speed and velocity? What is acceleration and what are its units? How can we tell from a velocity-time graph if an object is accelerating or decelerating? What does the area under a velocity-time graph represent?Velocity is speed in a given direction (units – m/s).Two objects may travel at the same speed but may have different velocities.Acceleration is the change in an object’s velocity per second (m/s2)Acceleration = change in velocity (m/s)Time taken for the change (seconds)The slope of the line on a velocity-time graph represents acceleration.The area under the line on a velocity-time graph represents distance travelled.
7 Acceleration a = acceleration (m/s2) v = final velocity (m/s) LO: understand how to draw and interpret graphs of motionAccelerationAcceleration can be calculated using the following equation:Change in velocityAcceleration =Time takenFinal velocity – initial velocityAcceleration =Time takenv - ua = acceleration (m/s2)v = final velocity (m/s)u = initial velocity (m/s)t = time (s)a =t
8 Using velocity-time graphs LO: understand how to draw and interpret graphs of motionUsing velocity-time graphsHow steep the line is (the gradient) on a velocity-time graph tells you the acceleration of that objectThe steeper the line, the greater the accelerationacceleration is measured in m/s2
9 Measuring the acceleration LO: understand how to draw and interpret graphs of motionMeasuring the accelerationChange in yGradient =Change in x∆yGradient =∆xThe gradient of a velocity time graph represent the acceleration of an object.
14 P2 2.1 Forces between objects What is the unit of force? What can we say about the forces acting on two interacting objects?When two objects interact, they always exert equal and opposite forces on each other.The unit of force is Newtons (N)
16 P2 2.2 Resultant forceWhat is a resultant force? What happens if the resultant force on an object is zero? What happens if the resultant force on an object is not zero?We can work out the effect of the forces on an object by replacing them with a single force called the resultant force.When the resultant force is zero, the object:-remains stationary OR- Moves at constant speed in the same direction
17 LO: calculate the forces acting on an object Resultant forceIf you have multiple forces acting on an object, you can replace them with one single force that has the effect of all the other forces combined together. This single force is called the resultant force
18 Rules for calculating the resultant LO: calculate the forces acting on an objectRules for calculating the resultantForces that act in the same direction can be added togetherForces that act opposite to each other must be taken awayForces that act vertically and horizontally CAN NOT be added and taken away from each other and MUST be considered separately.
19 Effects of forces - acceleration LO: calculate the forces acting on an objectEffects of forces - accelerationThe resultant force on a stationary (not moving) object is zero!The resultant force on an object travelling at a constant velocity is zero!If a resultant force is applied to an object, either moving or stationary, it will accelerate in the direction of the force
22 P2 2.3 Force and acceleration How is resultant force, acceleration and mass related to each other?Resultant force (N) = mass (kg) x acceleration (m/s2)F = ma
23 F m x a F = m x a Calculating forces F = force (N) m = mass (kg) LO: calculate the forces acting on an objectCalculating forcesF = m x aFF = force (N)m = mass (kg)a = acceleration (m/s2)m x a
24 W m x g W = m x g Weight is a force W = weight (N) m = mass (kg) LO: calculate the forces acting on an objectWeight is a forceW = m x gWW = weight (N)m = mass (kg)g = strength of gravity (m/s2)m x g
32 LO: understand the factors that affect the stopping distance of a car StreamliningMost of the resistance forces that act on a car are due to air resistance.Streamlining a car will increase the top speed, even if the engine is giving the same power output
33 P2 2.4 On the roadWhat is the resultant force on a vehicle travelling at constant velocity? What does the stopping distance of a vehicle depend on? What factors can increase the stopping distance of a vehicle?For any car travelling at constant velocity, the resultant force on it is zero.The braking force needed to stop a vehicle depends on a) the velocity of the vehicle and b) the mass of the vehicle.Stopping distance = thinking distance + the braking distanceFactors affecting stopping distances:Tiredness, alcohol, drugs, how fast the vehicle is travelling, adverse road conditions and poorly maintained vehicles.
34 Stopping distance = thinking distance + braking distance LO: understand the factors that affect the stopping distance of a carStopping distanceThe stopping distance of a car is the minimum distance that a car can safely stop inStopping distance = thinking distance + braking distance
35 What factors will affect LO: understand the factors that affect the stopping distance of a carThinking distanceThe thinking distance is the distance travelled by the vehicle in the time it takes for the driver to reactalcoholother drugs and some medicinestirednessWhat factors will affectThe thinking distancedistractions, such as mobile phonesspeed
36 What factors will affect LO: understand the factors that affect the stopping distance of a carStopping distanceThe stopping distance is the distance travelled by the vehicle during the time the braking force actsweathercondition of tyres/brakesWhat factors will affectThe stopping distancespeedcondition of road
40 P2 2.5 Falling objectsWhat is the difference between weight and mass? What is terminal velocity?The weight of an object is the force of gravity on it (Newtons, N)The mass of an object is the quantity of matter (kilograms, kg)Gravitational field strength on Earth = The force of gravity on a 1kg object on Earth.Weight (N) = mass (kg) x gravitational field strength (N/kg)As an object falls, its acceleration decreases as the drag force starts to increase. The object starts to travel at constant velocity – this is called terminal velocity.
42 Terminal Velocity Consider a skydiver: At the start of his jump the air resistance is ZERO so he ACCELERATES downwards.2) As his speed increases his air resistance will INCREASE3) Eventually the air resistance will be big enough to EQUAL the skydiver’s weight (force caused by gravity). At this point the forces are balanced so his speed becomes CONSTANT - this is called TERMINAL VELOCITY
43 Terminal Velocity Consider a skydiver: When he opens his parachute the air resistance suddenly INCREASES, causing him to start SLOWING DOWN.5) Because he is slowing down his air resistance will DECREASE again until it balances his WEIGHT. The skydiver has now reached a new, lower TERMINAL VELOCITY.
44 Velocity-time graph for terminal velocity… Parachute opens – diver slows downVelocitySpeed increases…Terminal velocity reached…On the MoonDiver hits the groundNew, lower terminal velocity reachedTime
49 P2 3.1 Energy, Work and PowerWhat do we mean by the word ‘work’ and ‘power’ in science? What is the relationship between work and energy? What happens to work done against frictional forces? How do we calculate gravitational potential energy?‘Work’ is done on an object if it moved by a force = energy transferredWork done (Joules, J) = force (N) X distance moved (m)Work done to overcome friction is mainly transformed into heat energyGravitational potential energy is a measure of the work done against gravity.GPE (J) = mass (kg) x gravity (N/kg) x height (m)Power is the amount of energy transferred each second.
50 Work done = force x distance LO: understand how energy can be transferredCalculating workThe work done by an object is equal to the amount of energy that it transfersWork done = force x distanceW = f x dW = work done(J)f = force (N)d = distance(m)
51 Gravitational Potential Energy LO: understand the nature of gravitational potential energyGravitational Potential EnergyGravitationalField strengthGPE = mass xx heightGPE = m x g x hGPE = gravitational potential energy (J)m = mass (kg)g = gravitational field strength (N/kg)h = height (m)
52 Power is the amount of work done/energy transferred in a given time LO: understand how energy can be transferredCalculating powerPower is the amount of work done/energy transferred in a given timePower = work done / timeP = W / tP = power (W)W = work done (J)t = time (s)
56 P2 3.2 Kinetic and elastic energy What are kinetic energy and elastic potential energy? How does the kinetic energy of an object depend on its speed? How can we calculate kinetic energy?Kinetic energy (J) = ½ x mass (kg) x speed2 (m/s)2Elastic potential energy is the energy stored in an elastic object when work is done on it to change its shape.
57 Kinetic energy KE = ½ x m x v² KE = kinetic energy (J) m = mass (kg) LO: understand the nature of kinetic energyKinetic energyKE = ½ x m x v²KE = kinetic energy (J)m = mass (kg)v = velocity (m/s)
60 LO: understand the link between force and extension of an object Stretching objectsWhen you stretch an object, work is done to change its shape. While it remains stretched the object stores elastic potential energyMost materials have a range where the force and extension are proportionalThe constant gradient here shows us that the force and extension are proportional
61 LO: understand the link between force and extension of an object Material propertiesBeyond a point, the material will start to show plastic behaviour.A small increase in force will give a large increase in extension. The deformation will be irreversible (the material will not go back to the original shape when the force is taken away)Beyond the proportional limit, the material shows plastic behaviour. The extension is now much harder to predict
62 Hooke’s Law Hooke’s law states that: LO: understand the link between force and extension of an objectHooke’s LawHooke’s law states that:The extension of an object is directly proportional to the force that is applied to it provided that the limit of proportionality is not exceeded
63 F = k x e Hooke’s Law Hooke’s law can be written as: F = Force (N) LO: understand the link between force and extension of an objectHooke’s LawHooke’s law can be written as:F = k x eF = Force (N)k = spring constant (N/m)e = extension (m)
67 P2 3.3 Momentum and impactHow can we calculate momentum? What is its unit? What happens to the total momentum of two objects when they collide? What is the impact force and how can it be reduced?Momentum of a moving object = its mass x velocityUnit is kilogram metre/second (kgm/s)When two objects collide momentum is conserved.The impact force can be reduced by using air bags and crumple zones.
69 P = m x v Momentum P = momentum (kgm/s) m = mass (kg) LO: understand what is meant by momentumMomentumP = m x vP = momentum (kgm/s)m = mass (kg)v = velocity (m/s)
70 Conservation of momentum LO: understand what is meant by momentumConservation of momentumIn a closed system, the total momentum before an event and the total momentum after an event are the same. This is called conservation of momentum.Events you may be asked about in your exams are:CollisionsExplosions
71 Brakes and crumple zones LO: explain how safety features on a car workBrakes and crumple zonesBrakes, air bags and crumple zones are the main safety features on a car.They increase the time taken for the impact.As F=ma and acceleration is change in velocity per second, the longer the impact time, the less force is transferred to the occupants of the car.
77 P2 4 Current Electricity.What are charge, current and potential difference and how are they linked? What is Ohm’s Law? What happens to current, potential difference and resistance in series and parallel circuits?Current is the flow of electrical charges around a circuit, measured in Amps (A).Potential difference is the difference in energy per change at two points in a circuit, measured in volts (V).Ohm’s Law states that Potential difference is proportional to current as long as the temperature remains constant.Ohm’s Law: V=IxRSeries circuits consist of one ‘loop’ of components through which electrical current can pass.Parallel circuits consist of many branches or paths for the electrical current to take.
78 What is an atom made up of? LO: understand static electricityWhat is an atom made up of?Protons – Positively charged particles found inside the nucleusNeutrons – Neutral particles found inside the nucleusElectrons – Negatively charged particles that orbit the nucleus
80 Static electricity by friction LO: understand static electricityStatic electricity by frictionWhen you rub one of the rods with the cloths, you create static electricity. This happens in one of two ways.For the polythene rod, the dry cloth transfers electrons TO the surface of the rod and gives it a negative charge
81 Static electricity by friction LO: understand static electricityStatic electricity by frictionWhen you rub one of the rods with the cloths, you create static electricity. This happens in one of two ways.For the perspex rod, the dry cloth transfers electrons away from the surface of the rod. This gives it a positive charge
82 Static electricity rules LO: understand static electricityStatic electricity rulesLike (The same) charges repelUnlike (The opposite) charges attract
83 Calculating current Current = Charge/time I = Q/t LO: Understand how to create electrical circuitsCalculating currentCurrent: This is the flow of electric charges around a circuit. The size of the current is dependent on the rate of flow of electric charges.Current = Charge/timeI = Q/tI = Current (Amps, A)Q = Charge (Coulombs, c)t = Time (s)
84 Calculating potential difference LO: Understand how to create electrical circuitsCalculating potential differencePotential Difference (Voltage): The potential difference between two points is the work done per unit charge between two pointsPotential difference = work done/chargeV = W/QV = P.D. (Volts, V)W = Work done (Joules, J)Q = Charge (Coulombs, c)
85 Energy = potential difference x Charge LO: Understand how to create electrical circuitsCalculating energyEnergy = potential difference x ChargeE = V x QE = Energy transferred (Joules, J)V = P.D. (Volts, V)Q = Charge (Coulombs, c)
88 LO: Understand the relationship-between current and voltage in a circuit Ohm’s LawOhm’s Law states that the current through a resistor is directly proportional to the potential difference (voltage) provided the temperature is constant
89 Potential difference = Current x Resistance LO: Understand the relationship-between current and voltage in a circuitOhm’s LawPotential difference = Current x ResistanceV = IRV = P.D. (V)I = Current (A)R = Resistance (Ohms, Ω)
93 Series circuitsIN A SERIES CIRCUIT, EVERYTHING IS CONNECTED END TO END. THERE IS NO PLACE FOR THE CURRENT TO SPLIT IN THE CIRCUIT.The current through each component in a series circuit is the sameThe potential difference of the source is shared out between the components in a series circuit
94 Parallel circuitsIN A PARALLEL CIRCUIT, THERE ARE BRANCHES THAT SEPERATE THE CIRCUIT INTO SMALLER CIRCUITS. THERE IS MORE THAN ONE PATH FOR THE CURRENT TO TAKE.The potential difference across each component is the same in a parallel circuitThe total current in the circuit is the sum of the currents through the individual components in the circuit
95 LO: Understand the relationship-between current and voltage in a circuit Non-Ohmic Components1An LED does not follow Ohm’s law and is designed to only allow current to flow through in one direction
96 LO: Understand the relationship-between current and voltage in a circuit Non-Ohmic Components2An LED does not follow Ohm’s law and will only light up when current to flows through in the right direction.If current tries to flow in the other direction it encounters a MAHOOSIVE resistance!
97 P2 5 Mains Electricity.What is the difference between A.C. and D.C? The features of a Plug. How fuses and circuit breakers (RCCBs) work to make electrical appliances safe.Alternating current (A.C.) oscillated forwards and backwards.Direct Current (D.C.) only flows in one direction.A 3 pin plug contains a live, neutral and earth wire, along with a fuse, and cable grip.Fuses melt when too much current passes through them, breaking the circuit.Circuit Breakers measure the difference between the live and neutral wires and ‘trip’ when this is too big.
98 LO: describe features of mains electricity AC vs DCIf you turn on any battery powered device the electricity will only ever flow in one direction.This is called DIRECT CURRRENT (d.c.) as the electricity goes around in just one direction.
99 Direct current is what comes out of a battery Direct current is what comes out of a battery. It only flows in one direction and should remain at a constant value throughout the life of the battery. If you connected this sort of supply to an oscilloscope it would look like this.Voltage / Vtime
100 LO: describe features of mains electricity AC vs DCHowever, the same isn’t true for mains electricity. Mains electricity uses ALTERNATING CURRENT (a.c.) which repeatedly flows in one direction and then reverses its flow. The frequency is how many times it changes direction in one second
101 Frequency (Hz) = 1 ÷ time taken for one cycle (s) +320Mains voltage – 230V – is an average pd, (root mean square pd) by dividing peak voltage by root2.One cycle(1/50th second)-320Frequency (Hz) = 1 ÷ time taken for one cycle (s)
104 Key points Mains electricity uses a.c. Mains electricity is at 230V LO: describe features of mains electricityKey pointsMains electricity uses a.c.Mains electricity is at 230VMains electricity has a frequency of 50Hz. This means it changes direction 50 times in one second
105 LO: describe features of mains electricity Cables and PlugsCables and wires are designed to allow people to use them without risk of hurting themselves. Most appliances are supplied with three-core cable. This means the cable is made up of three separate wires.
106 Components of a plug and cable LO: describe features of mains electricityComponents of a plug and cableLive wire (brown) – This carries the current to the appliance.Neutral wire (blue) – This completes the circuit and is usually at 0VEarth wire (green/yellow) – This ‘earths’ the appliance in case of a faultFuse – This stops the flow of current if it gets too high
109 LO: describe features of mains electricity EarthingComponents are earthed to make sure you don’t get an electric shock if the live wire accidentally touches the casing. The electricity will flow harmlessly through the earth wire instead of through you when you touch the casing.However, appliances with plastic cases (hairdryers etc.) don’t have earth wires.
110 LO: describe features of mains electricity FusesA fuse is a component that has a wire running through it made of a different material/thickness than the rest of the circuit. It is designed to stop current that is too high flowing through it.
111 LO: describe features of mains electricity FusesFuses have a rating based on the amount of current they will allow through. For example, a 13A fuse will allow a maximum of 13 amps of current to flow through. If MORE than this tries to flow through, the wire heats up and melts, breaking the circuit and protecting the appliance
112 What happens if the current is too large? The Circuit breakerswitchelectromagnetWhat happens if the current is too large?Too much currentcauses the electromagnet to produce a magnetic field strong enough to open the switch.(The circuit break is said to ‘trip’).This switches off the current.
113 LO: describe features of mains electricity Circuit BreakersCircuit breakers are fitted in newer homes. They measure the difference in current in the live and neutral wires. If the difference is too great, an electromagnetic switch opens (‘trips’) which stops the flow of current. They work a lot faster than fuses and can be reset easily
114 Calculating electrical power LO: describe features of mains electricityCalculating electrical powerPower = Potential difference x CurrentP = V x IP = Power (w)V = P.D. (V)I = Current (A)
115 2 (a) (iii) The bulb is at full brightness when the potential difference across the bulb is 12 V. The current through the bulb is then 3 A.Calculate the power of the bulb when it is at full brightness and give the unit.Use the correct equation from the Physics Equations Sheet.Power =(3 marks)
116 P2 6 Radioactivity.The discovery of the nucleus. The different types of ionising radiation. What happens during nuclear fission and nuclear fusion. How to calculate half life.Rutherford discovered the presence of the nucleus after preforming his alpha scattering experiment.Ionising radiation occurs in the form of alpha particles, beta particles and gamma waves.In nuclear fission, heavy unstable nuclei split to release ionising radiation and lots of energy.In nuclear fusion, helium nuclei fuse to become hydrogen nuclei, creating LOTS of energy.Half life is the time taken for half of a quantity of radioactive isotope to decay, It is useful in dating materials.
118 The Plum Pudding Model - 1897 LO: understand the nature of radioactive decayThe Plum Pudding Model
119 LO: understand the nature of radioactive decay Enter RutherfordErnest Rutherford fired alpha particles at gold foil. Alpha particles have a positive charge and he expected them to go through the particle, with a small amount of deviation from their path
120 Gold Foil Experiment - 1911 The results are very different! LO: understand the nature of radioactive decayGold Foil ExperimentThe results are very different!Most alpha particles go straight through with no deviation! Some, however, are diverted through very large angles! The physics community is flummoxed by this finding!
121 Gold Foil Experiment - 1911 The results are very different! LO: understand the nature of radioactive decayGold Foil ExperimentThe results are very different!Most alpha particles go straight through with no deviation! Some, however, are diverted through very large angles! The physics community is flummoxed by this finding!
122 SUGGESTS THAT MOST OF THE ATOM IS EMPTY SPACE!! LO: understand the nature of radioactive decayConclusionsMost of the fast, highly charged alpha particles went whizzing straight through undeflected.SUGGESTS THAT MOST OF THE ATOM IS EMPTY SPACE!!
123 LO: understand the nature of radioactive decay ConclusionsSome of the alpha particles were deflected back through large angles. A very small number of alpha particles were deflected backwards!SUGGESTS THAT THERE IS A CONCENTRATED POSITIVE MASS SOMEWHERE IN THE ATOM.
124 A very small number of alpha particles were deflected backwards! LO: understand the nature of radioactive decayConclusionsA very small number of alpha particles were deflected backwards!SUGGESTS THAT THE CONCENTRATED MASS IS MINISCULE COMPARED TO THE SIZE OF THE REST OF THE ATOM, BUT CONTAINS MOST OF THE MASS
126 LO: understand the nature of radioactive decay Types of RadiationThere are three different kinds of radiation. Each one has a unique nature and penetrationAlpha radiation:This particle is made up of two protons and two neutrons (i.e. a Helium nucleus). It has a charge of +2 and moves slowly because of it’s large mass. It can be stopped by a few cm of air or by a piece of paper
127 LO: understand the nature of radioactive decay Types of RadiationThere are three different kinds of radiation. Each one has a unique nature and penetrationBeta radiation:During beta radiation, a neutron turns into a proton inside the nucleus and gives off an electron, which is fired from the nucleus. The electron is small and light and so moves very fast! Beta particles can be stopped by a thin sheet of aluminium
128 LO: understand the nature of radioactive decay Types of RadiationThere are three different kinds of radiation. Each one has a unique nature and penetrationGamma radiation:Gamma radiation usually follows alpha or beta decay. It is NOT a particle like the other two. It is a high energy EM wave that travels at the speed of light (the fastest that anything can travel Joel). It can only be stopped by a very thick piece of lead or concrete.
129 LO: understand the nature of fusion and fission IsotopesAn isotope of an element has the same number of protons and neutrons as the original, but a different number of neutrons.
130 Radioactivity of a substance LO: understand the nature of fusion and fissionRadioactivity of a substance
131 Radioactivity of a substance LO: understand the nature of fusion and fissionRadioactivity of a substanceAs a radioactive substance decays, the number of particles left in it will start to reduce. Therefore the radioactivity of the substance will begin to decrease. It will continue to decrease, until the radioactivity has reached zero!
132 LO: understand the nature of fusion and fission Half-lifeThe half-life of a substance is the time it takes for HALF of the particles in a sample to decay or for the radioactivity of a substance to decrease by HALF.
137 HOW does It work? Nuclear Fission LO: understand the nature of fusion and fissionNuclear FissionNuclear fission is a process that uses atoms to generate VAST amounts of energy.HOW does It work?
138 A slow moving neutron is fired at the Uranium. LO: understand the nature of fusion and fissionNuclear FissionTo begin with, we have a simple Uranium nucleus. Uranium is used because it is already unstable.A slow moving neutron is fired at the Uranium.NeutronUranium nucleus
147 LO: understand the nature of fusion and fission Where does this happen?The sun is made up of mainly hydrogen. The high temperature on the sun allows the hydrogen to fuse together and make helium, releasing massive amounts of energy in the process
148 P2 7 Stars.The features of the life cycle of a main sequence star like the sun. What could happen in the life of a star larger than then sun.Main sequence stars go through the following stages:Nebulae – protostar – main sequence – red giant – white dwarf – black dwarf.Larger stars could form super red giants, these will then turn in to a supernova – neutron star/black hole.
150 LO: understand the lifecycle of a star NebulaAll stars start their lives as part of a nebula. Nebulae are large clouds of dust and gas (mainly hydrogen).
151 LO: understand the lifecycle of a star ProtostarOver millions of years, gravity will cause the dust and gas in the nebula to come together. As it does this, the temperature increases until hydrogen can fuse. When this happens, a protostar is born. This is kind of like a ‘baby’ star.
152 LO: understand the lifecycle of a star Main sequence starThe main sequence star is the next stage after a protostar. Hydrogen fusion is now in full flow and the star is much hotter and brighter than the protostar.
153 LO: understand the lifecycle of a star Red Giant starWhen a star runs out of hydrogen, it begins to fuse other, heavier elements. This releases more energy, causing the star to expand. It also gives off red light, giving it the name ‘Red Giant’.
154 LO: understand the lifecycle of a star White dwarfWhen the red giant has run out of all fuel and can fuse nothing more, it will lose its outer layers. This leaves just the core, which is still extremely hot. It is so hot it glows white hot, giving the name to this stage – the ‘white dwarf’.
155 LO: understand the lifecycle of a star Black dwarfAfter a long enough time, the white dwarf will cool down enough so that it stops glowing white hot. It is now called a ‘black dwarf’.
156 LO: understand the lifecycle of a star Red Super Giant starFollowing the main sequence, the star begins to fuse together heavier elements. However, as it has far more fuel, it expands to a much larger size and gives off much more energy.
157 LO: understand the lifecycle of a star SupernovaFor very heavy stars, once they have run out of fuel, the star begins to collapse in on itself. It continues to collapse until it reaches a critical point when it can’t collapse any more. This causes a MASSIVE shockwave!
158 LO: understand the lifecycle of a star SupernovaThe shockwave is so large that the outer layers EXPLODE outwards! The explosion only lasts seconds, but can release as much energy in those seconds as the star has released up to that point! It can be as bright as the light from 10billion stars.
159 LO: understand the lifecycle of a star Neutron starAfter a supernova, only the star’s core is left behind. During the collapsing process, this core is turned into just neutrons.The resulting ‘neutron star’ is very very dense. One spoonful of a neutron star would weigh more than the Earth!
160 LO: understand the lifecycle of a star Black holeIn some very very rare cases, the core of a star left over after a supernova will continue to collapse. It will keep getting smaller and smaller until the whole star has collapsed into an infinitely small point.
161 LO: understand the lifecycle of a star Black holeThis ‘singularity’ has an immense gravitational force. It’s attraction is so strong that not even light can escape from it. Hence the name ‘black hole’.