Paper 1 Overview Flashcards

Question

SP2d - What equation uses Newton's second law?

Answer 1

F = m x a | (Force = mass x acceleration)

Answer 2

* A measure of how difficult it is to accelerate an object. * The ratio of the force needed to accelerate an object over the acceleration produced. * If an object has a lerger inertial mass, it will require more force to produce a given acceleration than an object with a larger inertial mass.

Answer 3

* Attach masses to the end of the trolley hanging off the end of the table over the ramp and the pulley . * Set up two light gatesa measured distance apart. * Connect the light gates to a data logger. * Release that masses. using your data log information, divide the length of the card by the time the light gate was active for each of the light gates. * Divide the difference between these two velocities by the time between each of them to get the acceleration. * To investigate how mass affects this, repeat with different masses.

Answer 4

When objects interact the forces exerted are equal and opposite.

Answer 5

The downward force of weight from the person on the ground and the upward reaction force of the ground on the person.

Answer 6

Balanced forces all act on the same object, action-reaction forces act on different objects.

Answer 7

p = m x v | (momentum [kg m/s] = mass x velocity)

Answer 8

F = Δp / t (Force = change in momentum ÷ time) As F = m x a and a = Δv / t we can see that F = (m x Δv) ÷ t Since m x v = p then m x Δv = Δp So, F = Δp ÷ t

Answer 9

* Total momentum before = total momentum after * Since momentum is vector, an object moving in the opposite direction has a negative momentum and this must be taken into account when calculating momentum.

Answer 10

* The total distance it takes for a car to stop once the driver reacts to an external stimuli. * This consists of: Thinking distance & braking distance

Answer 11

* 0.25 seconds. * This can be longer if the driver has taken drugs/ alcohol or hasn't had enough sleep

Answer 12

* Increasing its momentum: * If it is moving faster * Higher mass * Reducing friction: * Brakes are worn * Rain/ice/snow on the roads * Loose gravel

Answer 13

E = F x d KE = 1/2 x m x v² (1/2 x m x v²) ÷ F = d d = (m x v²) ÷ 2F Mass x velocity² divded by 2 force = braking distance [Also can be (p x v) ÷ 2F = d Momentum x velocity ÷ 2 Force = Braking distance]

Answer 14

* Air bags * Crumple zones and side impact bars (Easily give way causing themsleves to crush) * Seat belts

Answer 15

* F = Δp / t * All the safety features of a car absorbe kinetic energy, increasing the time taken for the momentum to reduce. * As the time is increased, the force is reduced.

Answer 16

* Kinetic * Thermal * Gravitational Potential * Elastic Potential * Sound * Light * Chemical * Nuclear * Electrical

Answer 17

* Heating * Forces * Electricity

Answer 18

* Energy cannot be created or destroyed, only transferred between stores. * In a closed system, the total start energy = the total end energy

Answer 19

Joules (J)

Answer 20

A sankey diagram, The width of the bars represent the amount of energy.

Answer 21

Dissipation

Answer 22

* Use a lubricant. * Moving parts cause friction which causes enrgy to dissipate losing energy. * Lubrication reduces friction and thus energy loss by friction.

Answer 23

total useful energy output / Total energy input Efficiency is on a scale of 0 to 1. To calculate it s a percentage, x100

Answer 24

The useful energy has an arrow going staright while the wasted energy arrow turns off.

Answer 25

Part of a fluid (Liquid/gas) that is warmer than the rest rises up once it reaches the top it looses thermale enrgy and sinks back down. This forms a current.

Answer 26

* When thermal energy wants to travel it requires particles to travel throgh. * It gives energy to these particles which causes heat. * A cavity in the wall means that there is air in which particles will collide less and heat will pass through less, so heat can't escape as easily.

Answer 27

* Silver coating on the outside and inside reflects radiation which would transfer thermal energy * Glass walls with vacuums between create a cavity stopping heat from entering or escaping * Plastic stopper stops heat from escaping

Answer 28

ΔGPE = m x Δh x g (change in GPE is mass x change in height x gravitational field strength)

Answer 29

9.81 (Can be rounded to 10) m/s² or N/Kg

Answer 30

KE = ½ x m x v² (Kinetic energy = mass x velocity² divided by 2)

Answer 31

* As an object looses height, it looses GPE this 'lost' energy transfers, mostly, into kinetic energy as it is moving. * Some other energy may transfer into sound energy

Answer 32

* Fossil fuels: * Natural gas * Coal * Oil * Nuclear

Answer 33

It releases Carbon dioxide and other gases that are harmful for the environment as they contribute to climate change.

Answer 34

**Pros**: * Will never run out * Won't release carbon dioxide once installed **Cons**: * Energy output depends on sun and so may not always be available

Answer 35

**Pros**: * Will never run out * Won't release carbon dioxide once installed **Cons**: * Many have to be installed and they have low output * Takes up large spaces and soem say this spoils the view * Not reliable

Answer 36

**Pros**: * Very reliable * Will never run out * Won't release carbon dioxide once installed **Cons**: * Habitats destroyed * Only useful when water sources are nearby

Answer 37

**Pros**: * Extremely reliable * Will never run out * Won't release carbon dioxide once installed **Cons**: * Some argue that it harms wildlife

Answer 38

**Pros**: * Reliable * Will never run out * Won't release carbon dioxide once installed **Cons**: * Small scale and experimental * Low output

Answer 39

**Pros**: * Will never run out * Won't release carbon dioxide once installed * Extremely reliable **Cons**: * Only useful near volcanic sites

Answer 40

**Pros**: * Will never run out * Carbon neutral (Burning fuels releases carbon put planting plants took in carbon so its neutral) * Useful as they can power vehicles **Cons**: * Can take up space that could be used for food, this can increase the price of food.

Answer 41

* Paritcles vibrate perpendicular to their direction of travel. * They transfer energy * They all travel at the same speed in a vacuum (3x10⁸) * All EM waves are examples of this * Water waves are transverse

Answer 42

* Particles vibrate parallel to direction of travel * Areas of compression and rarefraction * Sound waves * Seismic P waves

Answer 43

1. The amount of waves passing in a second (measured in Hertz Hz. Determines pitch or colour) 2. The time it takes one wave to pass a point 3. The length in m from one point to the next identical point of a wave 4. The distance in m from a waves rest position to its trough or peak

Answer 44

v = d/t (Velocity = distance ÷ time) v = f x λ (Velocity = frequncy x wavelength)

Answer 45

* Measure the distance the buoys are apart. * Record the amount of time it takes for a single wave to get from one to the other. * Do distance/time to get the wave speed.

Answer 46

* Set up a wave tank filled with water and a straight dipper with a ruler along the side * Vary the voltage provided to the straight dipper till there are at least 2 waves visible at any point * Count how many waves form in 10 seconds and divide by 10 to get your frequency * Using the ruler estimate the wavelength of a wave * Frequency x wavelength * Alternatively, record how long it takes the wave formed to travel a certain distance and to distance/time

Answer 47

* Suspend a metal rod using clamp stands * Hold a smartphone with a frequency app at one end * Hit the other end of the rod with a hammer and record the peak frequency * Meausure the length of the rod * Frequency x wavelength

Answer 48

* When a ray of light reaches an interface (boundary) between substances, it changes speed (because light's speed is dependant on the density of the substance it travels in). * If it slows down it bends towards the normal and if it speeds up it bends away

Answer 49

* Waves of water travel faster is deeper water than shallow water * They also are longitudinal so can be represented with lots of parallel lines rather than one line * When the wave of water reaches a boundary between shallow and deep, the part of each line that is furthest ahead, will reach the boundary first and slow down first. * This gradual change in which parts slow down means that the wave bends towards the normal

Answer 50

* Reflect: The waves bounce off * Refract: The wave passes into the new material but changes direction * Transmit: The wave passes through without being absorbed or reflected * Absorbed: The wave disappears as the enrgy it was carrying is transferred into the material

Answer 51

Each frequency of light changes speed at a slightly different rate meaning that at the right angles they can be split up

Answer 52

* Sound waves enter the ar canal which focuses it * The eardum is a thin membrance which vibrates due to the soundwaves' vibrations * Vibrations are passed on to tiny bones which amplify the vibrations * Vibrations are passed on to the liquid inside the cochlea * Tiny hairs inside the cochlea detect these vibrations and convert them to electrical impulses * Impulses travel along the auditory nerve to reach the brain

Answer 53

* The cochlea has a membrane covered with hair cells * Each hair cell is connected to a neurone so that when it detects a vibration of its frequency it creates and electrical signal * The cochlea is a spiral with the outmost part (the base) detecting hgih frequencies (up to 20000Hz) and the low end (the apex) detecting lower frequencies (down to 20Hz)

Answer 54

* As people get older, the hairs of the base and apex of their cochlea can get damaged. * This means that they are no longer able to convert vibrations into impulses * Thus they can't hear these sounds

Answer 55

20Hz - 20,000 Hz

Answer 56

Sound above 20,000 Hz

Answer 57

* To find the depth of the water beneath them. * They fire off an ultrasound wave at 1500m/s. * They time how long it takes to return. * They use d = s x t to find out the distance hte wave travelled and divide it by 2 to find the depth of the water

Answer 58

* A probe emits ultrasound waves * Gel is used to stop it from reflecting * Some waves are reflected when they meet bones, fat, tissue etc. * The probe also detects these refelected waves * It sends these as impulses to the computer * The ultrasound imaging machine detcts the frequency of the impulses turning it into an image

Answer 59

* Other scans such as PET and CT would release radiation * This could harm the foetus causing mutations

Answer 60

Sound below 20Hz

Answer 61

* P waves: Longitudinal * S waves: Transverse

Answer 62

Vibrations produces by earthquakes

Answer 63

* P waves are longitudinal while S waves are transverse * S waves can only be transmitted by solids but P waves can go through all through states * The earth has a liquid outer core * S waves fired from a point can't go throuhg the liquid core but P waves can * This means that S waves have a larger shadow zone * Using the idea that S waves can't go through liquids and P waves can, scientists were able to find out about the structure of the earth

Answer 64

The area where a wave cannot reach when fired from a point

Answer 65

They get refracted

Answer 66

They can be reflected by the solid inner core

Answer 67

Seismic waves can be detected by seismometers and give information about where earthquakes are originating

Answer 68

* Reflection * Refraction

Answer 69

* i: Angle of incidence (between incident ray and the normal) * r: Angle of reflection/refraction (between reflected/refracted ray and the normal)

Answer 70

i = r (Angle of incidence = angle of reflection) This is the law of reflection **This is only for reflection and not for refraction**

Answer 71

The line drawn perpendicular to the object light is reflecting off (or refracting through)

Answer 72

* TIR occurs when light refracts through a substance at sucha low angle of incidence that it doesn't leave the other side * This angle is called the critical * If light enters at the critical, it will move along the interface * If light enters at an angle smaller than the critical, it will cause TIR to happen

Answer 73

* Place a ray box with a slit in front of it on a piece of paper * Place a glass box the way of the ray of light thta is being produced * Draw around the glass block * Mark the point of entry and exit for the light aswell as two further points (such as origin and edge of paper) on the piece of paper * Use your markings to draw lines representing the travel of the ray of light * Repeat with ray box at different angles and compare your results

Answer 74

* Specular: When light is reflected evenly on a smooth surface * Diffuse: When light is reflected in all directions on a rough surface

Answer 75

* Sunlight is made up of white light as it contains all the colours of the visible spectrum * An object that appears green will reflect the green part of the spectrum but reflect all the other colours

Answer 76

A blue filter would only transmit the blue part of the light that goes to it.

Answer 77

* They are all transverse waves * They all travel at (3x10^8m/s) ina vacuum * They transfer energy

Answer 78

* A prism was used to refract white light into the seven componenets. * A thermometer was placed just outside of the red part of this spectrum. * Another was placed in the spectrum. * The thermometer next to red was warmer suggesting there was something warming it up

Answer 79

**ROYGBIV** * **R**ed * **O**range * **Y**ellow * **G**reen * **B**lue * **I**ndigo * **V**iolet

Answer 80

* Gamma rays * X-rays * Ultraviolet * Visible light * Infrared * Microwaves * Radio waves

Answer 81

EM waves of different length get absorbed by different amounts by the atmosphere

Answer 82

* Heating food * Short range communication such as TV remotes * Security systems

Answer 83

* Communications and satellite transmissions * Heating up food and giving it energy

Answer 84

* Transmitting radio broadcasts * Radio communications via satellites

Answer 85

* Oscillations in electrical signals. * Metal rods can be used as aerials because they can absorb and transmit these oscillations

Answer 86

* The way radio waves and microwaves travel is dependant on the angles they reach the ionosphere. * At all angles, microwaves pass straight through and so there is maximum range they can be fired in a straight line. * At some angles, radio waves are reflected by the ionosphere, becasue they have larger wavelengths. * This means they don't have to be fired directly to a point

Answer 87

* Disinfect waters by killing microorganisms * Invisible ink due to fluoresence * Security on bank notes

Answer 88

Imaging of the inside of the body

Answer 89

* Radiotherapy * Sterilisation of medical equipment and food * PET scanner

Answer 90

* Infrared radiation is absorbed by our body. * We feel it as heat and an excess of it can destroy cells burning skin

Answer 91

It can cause sunburn and damage to DNA which can lead to skin cancer

Answer 92

They can lead to mutations causing cancer.

Answer 93

* They are ionising radiation. * They large amounts of energy due to high frequencies and short wavelengths which can pass through our skin.

Answer 94

* All objects emit the same amount of radiation that they absorb. * Hotter objects will emit more radiation than cold objects in the same time

Answer 95

The amount of radiation it absorbs from the sun must be equal to the amount of radiation that the earth radiates into space

Answer 96

* Energy from the sun is absorbed by the earth. * The earth radiates this into the atmosphere * Greenhouse gases in the atmosphere absorb this energy keeping it in the atmosphere * This means that the earth doesn't radiate into the atmosphere the same amount of energy it absorbed * Thus the temperature of the earth rises

Answer 97

* Pour water at 80° into four boiling tubes * Cover each with one of the surfaces * Put a thermometer in each * Time it and record the temperautre at regular intervals * The one that has the largest drop in temperature emits the most energy and thus must also absorb the most energy * You would expect the results to be from largest to smallest change: 1. Dull grey 2. Dull black 3. Shiny black 4. Shiny silver

Answer 98

A lens is a small piece of transparent material made to refract light in a certain way The power of a lens is how much it refracts light and is dependant on the shape and thickness of the lens

Answer 99

* Converging: Fatter in the middle and thinner at the top and bottom. Rays of light **converge** onto a focal point * Diverging: Fatter at the top and bottom and thinner in the middle. Rays **diverge** away from each other once they pass through

Answer 100

F is the focal length, i.e the length between the lens and its focal point

Answer 101

* Real image * Inverted * Less than 2F from other side of lens * Smaller size * (camera, eyes)

Answer 102

* Real image * Inverted * 2F from other side of lens * Same size * (Photocopier)

Answer 103

* Real image * Inverted * More than 2F from other side of lens * Larger size * (Projector)

Answer 104

* Virtual image * Right way up * Further than F on the **same side** of the lens * Larger size * (Magnifying glass, mirror)

Answer 105

* Virtual image * Right way up * Less than F on the **same side** * Smaller size

Answer 106

Real images: * **Can be projected onto a screen** * Same way round * Appears on the opposite side of the lens * Only produced by converging lenses * e.g. Projectors Virtual images: * **Can't be projected onto a screen** * Inverted (left-to-right) * Appears on the same side of the lens * Produced by diverging and converging lenses depending on situation * e.g. Mirrors

Answer 107

The point where all the rays of light would converge onto and meet.

Answer 108

Made of positively charged mass with negatively charged electrons scattered throughout.

Answer 109

* The gold foil experiment. * He fired alpha particles through various substances e.g. thin gold foil. * Firing alpha particles from a source and having a detector behind whatever substance he used so that he could find out if the particles pass through.

Answer 110

* Most particles passed straight through * Some were deflected slightly * Others were bounced back * This means that most of an atom is empty space. * Aditionally, atoms have a concentrated area of positive charge. * This is why some were reflected back.

Answer 111

* N: 1x10^-15 * A: 1x10^-10 (Atom is 10,000 times bigger)

Answer 112

P: * Inside nucleus * +1 charge * mass of 1 N: * Inside nucleus, * no charge * mass of 1 E: * Orbiting nucleus * -1 charge * mass of 1/1835 (negligible)

Answer 113

* The number of protons in the nucleus. * Different elements have different proton numbers

Answer 114

* The mass of the atom. * Protons plus neutrons.

Answer 115

Two atoms of the same element with different masses (Same atomic number but different mass numbers)

Answer 116

* An electron can move to a higher orbit. * When it returns back to its orbit it emits energy in the form of visible light. * The wavelength (and therefore colour) depends on the change in orbit.

Answer 117

* An emission spectrum. * A black line spectrum with coloured lines along it displaying which wavelengths were emitted.

Answer 118

* The coloured areas on the emission spectrum will be blacked out on the absorption spectrum and vice versa. * This means that the wavelengths that are emitted are also the wavelengths that are absorbed.

Answer 119

* The atom can loose an electron. * This is called ionisation as the atom has become an ion

Answer 120

An atom that is charged due to a gain or loss of electrons.

Answer 121

Ionising radiation

Answer 122

Radiation that is constantly all around us at a safe level.

Answer 123

* Medical * Ground and buildings * Food and drink * Radon gas * Cosmic rays * Nucelar

Answer 124

Radon gas just under 50%

Answer 125

* With a Geiger * Mueller tube / counter Meausres the count rate * Photographic film (badges called dosimeters) Gets darker / changes colour as its exposed to more radioactivity

Answer 126

Measure the background radiation so you can take this away from the radiation that you measure or else you value will be the source's radiation + the background radiation.

Answer 127

A helium nucleus consisting of 2 protons and 2 neutrons

Answer 128

An electron

Answer 129

A position (A positive electron)

Answer 130

Since it is an EM wave and not a particle, it doesn't have a charge.

Answer 131

* Alpha (Most) * Beta (+/-) * Gamma (Least) Since alpha particles are emitted at high speeds thay carry most energy and are best at ionistation. This is the opposite for Gamma.

Answer 132

* Gamma (Most) * Beta (+/-) * Alpha (Least)

Answer 133

* Alpha: paper/skin/few cm of air * Beta: few m of air/3mm of alluminium * Gamma: few Km of air/ few cm of lead/ several m of concrete

Answer 134

An unstable nucleus looses 2 protons and 2 neutrons (an alpha particle) causing its mass number to decrease by 4 and its atomic number to decrease by 2.

Answer 135

A neutron decays into a proton and a high energy electron.

Answer 136

A proton decays into a neutron and a high energy positron.

Answer 137

An unstable nucleus emits a gamma ray becoming more stable.

Answer 138

* The time it takes for half the unstable nuclei of a substance to decay * The time it takes for the count rate of a radioactive substance to decrease by half.

Answer 139

8/2 = 4 2⁴ = 16 128/16 = 8 8Bq

Answer 140

Irradiating fresh produce makes it safer to eat and increases its life time.

Answer 141

* To detect and treat cancer (radiotherapy and PET scans) * To sterelise equipment

Answer 142

* A gamma source is added to water and passed through the pipe and a geiger tube is placed on top. * Areas with leaks have higher levels of radiation.

Answer 143

* A beta source is placed on one side of the paper and a detector on the other. * When the detector detects too few beta particles passing through, the paper is too thin and so adjusts the force applied to the paper. * When too many pass throught the opposite happens.

Answer 144

Because they can be passed down through generations

Answer 145

* Using tongs * Not pointing the source at people * Storing the source in lead lined containers

Answer 146

* Increasing their distance * shielding the source * Minimising time spent near the source * Wearing dosimeter badges to monitor exposure

Answer 147

Ones with short half - lives

Answer 148

A substance becomes irradiated if exposed to a radioactive source but is contaminated if it is still radioactive even when the source is taken away.

Answer 149

* Water and soil nearby gets contaminated which contaminates the crops and plants. * Animals that feed on this also become contaminated,

Answer 150

* A radioactive tracer with a short half - life is injected into the blood stream. * The gamma camer detects areas of high radiation. * This can help in diagnosing internal bleeding. * The tracer is made using radioactive glucose molecules because cancer cells take up glucose quickly.

Answer 151

* A tracer that has beta plus decay is injected into the patient. * When the emitted positron meets an electron, they annihilate each other and release two gamma rays in opposited directions. * The PET scnanner moves around the patient detecting where gamma radiation originates from forming a series of images.

Answer 152

A beta emitter is placed next to the tumour inside the body.

Answer 153

Several beams of gamma rays, X-rays or protons are fired at the tumour from multiple directions.

Answer 154

Internal radiotherapy can harm can harm healthy cells while external radiotherapy specifically targets the cencer cells. Internal radiotherapy is only used in situations where the benefit greatly exceeds the risk.

Answer 155

**Pros**: * Sources of uranium will take a lng time to expire * They store mre energy per kg * They cause less deaths * The stations themsleves don't release GH gases **Cons**: * The extraction process release many GH gases * Waste substances can contaminate environment if not stored properly * Very expensive to decomission safely * Nuclear accidents cause many deatsh and long term effects

Answer 156

When an unstable nucleus absorbs a neutron, it decays releasing two smaller daughter nuclei, neutrons and energy.

Answer 157

A chain reaction

Answer 158

* CR: Rods that contain elements that absorb neutrons. Can be lowered or raised to control how much reation is taking place and how much energy is generated. * M: Material which slows down neutrons. This allows the neutrons to be absorbed increasing rate of reaction

Answer 159

* Thermal energy is generated from the reaction process. * This is used to heat up a source of water turning it into steam. * This steam turns turbines which turn and power the generator generating electricity.

Answer 160

Nuclear fusion occurs when two smaller nuclei (typically hydrogen) join together to form a larger atom (helium) and energy in the form of gamma radiation

Answer 161

* Nuclear fusion requires that the nuclei are travelling at over 1,000,000 m/s and in temperatures hotter than the sun. * This is to overcome the electrostatic repulsion that would otherwise repel the two like charged nuclei away from each other.

Answer 162

To maintain conditions required to overcome elctrostatic repulsion is extremely costly and hard to sustain on earth.

Answer 163

The model of our solar system in which everything orbits the earth.

Answer 164

The current model of our solar system where the sun is at the centre and other planes orbit it.

Answer 165

Elliptical

Answer 166

* Computers allow detailed analysis. * Photography allows accurate and permanent storage of events. * Telescopes can now be place outside of the earth's atmosphere giving wider and more detailed detection. * Space probes allow better analysis of the solar system.

Answer 167

* The earth's atmosphere absorbs many waves of the EM spectrum. * Outside the atmosphere, these could be detected. (such as infrared radiation)

Answer 168

Your weight is the force acting on you dependant on your mass and the gravitational field strength.

Answer 169

9.81 N/Kg | (Can be rounded to 10N/Kg)

Answer 170

* Highly elliptical * Circular geostationary * Low earth orbits * Polar orbits

Answer 171

* Satellites that stay in the same place relative to the earth's position. * They move at 3070 m/s and are used for broadcasting.

Answer 172

Polar orbits

Answer 173

Low earth orbits

Answer 174

Highly elliptical orbits

Answer 175

The gravitational force between the earth and the satellite causes it to continuously change direction and orbit the earth.

Answer 176

* The gravitational force on an object in a lower orbit is a stronger than at a higher orbit so a satellite at a lower orbit would have to travel at a higher speed to stay in orbit. * Once it eventually slows down, it will drop towards earth. * However as it drops it gains speed and will eventually be able to be at a lower orbit at a faster speed. * Once it drops enough that it passes through the earth's atmosphere, the air resistance will slow it down and it will eventually fall to earth.

Answer 177

Nuclear fusion | (typically H + H = He)

Answer 178

* It starts with a Nebula (A cloud of gas). * The particles in this pull themselves together, becoming denser until their own gravity causes it to collapse in on itself forming a protostar. * Eventually the pressure and temperature in the protostar become large enough that nuclear fusion starts to occur converting hydrogen to helium * The energy released form the fusion reactions push the star outward causing it to expand. * Once the force of the gravity pulling the star inwards matches the force of pressure from the fusion reactions, the star will be at a steady size and in its main sequence stage where it continues to convert hydrogen to helium * Eventually, hydrogen runs out and heavier reactions take place. * This creates more energy which expands the star more * The outermost layers are no longer held in place by the force of gravity so they expand forming a red giant * Once all the fuel has run out, all the layers disband forming a shell of gas. * This leaves behind a highly dense white dwarf which doesn't carry out any reactions.

Answer 179

* It starts with a Nebula (A cloud of gas). * The particles in this pull themselves together, becoming denser until their own gravity causes it to collapse in on itself forming a protostar. * Eventually the pressure and temperature in the protostar become large enough that nuclear fusion starts to occur converting hydrogen to helium * The energy released form the fusion reactions push the star outward causing it to expand. * Once the force of the gravity pulling the star inwards matches the force of pressure from the fusion reactions, the star will be at a steady size and in its main sequence stage where it continues to convert hydrogen to helium * Eventually, hydrogen runs out and heavier reactions take place. * This creates more energy which expands the star more forming a red supergiant. * These heavier fusions are carried out all the way to iron when it runs out of fuel. * The star rapidly collapses causing a supernova * This leaves behind a very dense neutron star * If the mass of the star is even larger, then a black hole is formed in place of the neutron star.

Answer 180

When the pitch of a noise get lower as it travels aways from you. (and higher when it travels towards you)

Answer 181

As a sound travels, the wavelengths are squashed or stretched meaning the sound's pitch appears higher or lower.

Answer 182

When light form distant galaxies shift towards the red side of the spectrum due to wavelengths being stretched as the galaxy moves away from earth.

Answer 183

Absorption spectrums of the galaxy compared to the absorption spectrum of the sun.

Answer 184

* The big bang theory * Steady state theory

Answer 185

* The whole universe started out from one point of concentrated energy. * All matter started form this point and continued to expand outwards as the universe constantyl expands.

Answer 186

The universe always existed and as it expands matter is continuosly created.

Answer 187

The Big Bang Theory

Answer 188

Red-shift; as galaxies are constantly moving away the universe is constantly expanding.

Answer 189

CMBR (Cosmic Microwave Background Radiation) is found throughout all of the universe at the same rate suggesting that it all started form one point and expanded out from there.

Answer 190

* A Currant bun has currants close together. * As the dough rises, the number of currants stay the same but they are found at consistent rate throughout the bun.

Answer 191

That galaxy is further away and moving faster than the other.