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126 Cards in this Set
- Front
- Back
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Define 'thinking distance'. |
Distance traveled before the driver can react and apply the brakes. |
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Define 'braking distance'. |
Distance traveled while the brakes are applied, before the car comes to a halt. |
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How do you work out the 'stopping distance'? |
Thinking distance + braking distance |
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List five factors in thinking distance. |
1. Age 2. Fatigue 3. Distractions (e.g. radio, phone) 4. Caffeine 5. Alcohol |
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Define momentum. |
The amount of mass in motion, or how difficult it is to stop something that is moving. Any moving object has momentum. |
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What is the formula for momentum? |
P = m X v Momentum = Mass X Velocity kg m/s = kg X m/s |
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Why is momentum a vector quantity? |
It has a size and direction. The momentum is the same direction as the velocity. |
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What does the idea of conservation of linear momentum dictate? |
The total amount of momentum is conserved during collisions i.e. the momentums before and after the collision are equal. |
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List all 9 types of energy. |
1. Kinetic 2. Thermal 3. Light/EM Energy 4. Sound 5. Gravitational Potential 6. Elastic Potential/Strain Energy 7. Electrical 8. Chemical 9. Nuclear |
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What is the principle of the conservation of energy? |
Energy can be changed from one form to another, but it can't be created or destroyed. |
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Define work/work done. |
The amount of energy it takes to move an object from one place to another. |
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What is the equality for work done? |
Work done = energy transferred |
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What is the formula for kinetic energy? |
KE = 1/2 X m X v(2) |
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What is the formula for Gravitational Potential Energy (GPE)? |
GPE = m X g X h GPE = mass X gravitational field strength X height |
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What is the formula for work done (energy transferred)? |
Work Done = force X distance |
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Define 'isotopes'. |
Atoms of an element with the same number of protons and electrons, but with different numbers of neutrons. |
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What isotopes of uranium are there? |
Uranium 235 and Uranium 238 |
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How do you calculate the number of neutrons in an isotope? |
Mass no. - atomic no. |
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How do you work out the number of electrons in an isotope? |
Their number is equal to that of protons (unless it's an ion). |
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How do you work out the number of protons in an isotope? |
It's the atomic no. (the number at the bottom). |
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Which uranium isotope is radioactive? What does this mean? |
Uranium 235 is a radioactive isotope. This means it's unstable and will decay at random, emitting ionising radiation in the form of alpha, beta and/or gamma. |
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What does it mean when an isotope decays? |
It changes into another type of atom and emits a type of radiation. |
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What is an alpha particle made from? What is their charge? |
A helium nucleus. + 2 |
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What is the speed of an alpha particle? |
Slow - 10% of the speed of light. |
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What can alpha particles be stopped by? Why? How could you describe their penetration level? |
They can be stopped by a few cm of air or a few sheets of paper. This is because anything they hit, they ionise and lose energy. This means they have low penetration. |
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How could alpha particles be very dangerous to somebody? |
If you ingested them. |
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How ionising are alpha particles? |
Highly ionising. |
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What is a beta particle made from? What is its charge? |
An electron. - 1 |
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What is the speed of a beta particle? |
Medium. |
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How can beta particles be stopped? How would you describe their penetration level? |
They can be stopped by a few sheets of aluminium foil. They have a medium penetration level. |
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How ionising are beta particles? |
Medium ionising. |
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What is a gamma wave made from? What is its charge? |
A high frequency EM wave. 0 |
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What is the speed of a gamma ray? |
The speed of light. |
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What can stop gamma rays? How would you describe their penetration level? |
They can be stopped by a few metres of concrete or a few cm of lead. They have a high penetration level. |
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How ionising are gamma rays? |
Low ionising. |
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Define nuclear fission. |
The reaction when the nucleus of a large atom e.g. uranium splits into two smaller nuclei. |
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Define chain reaction. |
The sequence of reactions produced when a nuclear fission reaction triggers one or more further fissions. |
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Describe the six steps of nuclear fission. |
1. A neutron is fired at a uranium nucleus. 2. The nucleus splits into two radioactive neutrons. 3. Heat and kinetic energy is released. 4. Three more neutrons are released. 5. Each of the 3 neutrons is absorbed by another uranium nucleus. 6. The chain reaction continues. |
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What are the two radioactive neutrons created by the splitting uranium nucleus called? |
Daughter nuclei. |
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What is an uncontrolled chain reaction? What can this create? Therefore, how is this type of reactions used? |
The process where all three neutrons will each be absorbed by a uranium nucleus. This can cause explosions and be very destructive. This is why they're used in nuclear weaponry. |
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What is a controlled chain reaction? What can this create? Therefore, how is this type of reactions used? |
The process where only one neutron is absorbed by a nucleus, while the other two are absorbed by other materials. By doing this, these substances are used without destructive explosions. This is why nuclear plants create these reactions to create nuclear energy. |
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What do boron control rods do in nuclear power reactor cores? |
Absorb neutrons, resulting in less fission and the slowing down of the rate of reaction. |
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When would the control rods go down? Why? |
When it's too hot in order to slow down the reaction rate. |
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What does slowing down the reaction rate allow for? |
Neutrons produced by fission reactions can be absorbed by other uranium atoms. |
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What are the fuel rods and control rods contained with in? What is it made of? |
A moderator usually made of graphite. |
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What does the moderator do? |
It slows down neutrons produced by nuclear fission so they can be absorbed by other uranium atoms. |
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TRUE OR FALSE
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FALSE They're very radioactive. |
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What is High Level Waste (HLW)? |
Fission product from uranium fuel. Also metal cylinders containing uranium fuel (becomes radioactive from fuel's radiation). |
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How radioactive is HLW? |
Very radioactive. |
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How long is HLW as radioactive as it is for? |
0 - 50 years. |
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What is Intermediate Level Waste (ILW)? |
Metal cylinders containing uranium fuel. |
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How radioactive is ILW? |
Moderately radioactive. |
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How long does ILW stay as radioactive as it is? |
50 - 10's of thousands of years into its creation. |
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What is Low Level Waste (LLW)? |
Clothes and cleaning materials from nuclear power stations. Hospitals where radiotherapy is used to treat cancer. |
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How radioactive is LLW? |
Slightly radioactive. |
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How long is LLW as radioactive as it is? |
10's of thousands of years into its creation. |
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How is HLW transported? Why? |
- Transported in thick concrete and steel containers, which absorbs radiation - Sealed in glass to stop radioactive material from escaping - Stored in canisters until it becomes ILW |
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How is ILW stored? Why |
Stored in thick concrete and steel containers, which absorbs radiation. |
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TRUE OR FALSE No ILW has been disposed of yet. |
TRUE |
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How is LLW stored? Why? |
Compacted and buried in special landfill sites because radioactive material could leak into soil or water otherwise. |
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What problems could come with firing nuclear waste into space? |
Launch vehicle may fall to Earth and spread radioactive material over a wide area. |
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What problems could come with dumping barrels of nuclear waste in the sea? |
Barrels corrode - would release radioactive materials into the sea and enter the food chain. |
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What problems would come with storing nuclear waste underground? |
Must be stable ground with a very low earthquake risk. |
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List 2 advantages are there to nuclear power. |
- Nuclear power stations don't produce CO(2) - Nuclear waste can potentially be stored |
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List 3 disadvantages of nuclear power. |
- Processes to make fuel rods need energy generated in a way that produces CO(2) - Waste must be stored for 10's of thousands of years until at safer levels. Nothing can leak to environment until then. - If reactors explode, wind can spread radioactive material over wide area before falling with rain (e.g. Chernobyl nuclear power station, Ukraine) |
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Describe the process of nuclear fusion. |
- Protons repel each other via electrostatic repulsion. - Push them together very hard with strong nuclear force. - Protons fuse and energy is emitted. |
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How much energy is released by combusting 1kg of hydrogen? |
197 x 10(^6^) J |
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How much energy is released by the fission of 1kg of uranium? |
81 000 000 x 10(^6^) J |
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How much energy is released by the fission of 1kg of hydrogen? |
630 000 000 x 10(^6^) J |
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List 3 advantages of nuclear fusion. |
- Most energetic process in the world. - Cheap fuel (H(2)O) and we won't run out of water to use as fuel (H atoms) for a LONG time - Much less radiation emitted in reaction than fission |
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What are 2 conditions required for nuclear fusion? |
- VERY high temperature (millions of degrees C) - High pressure/density |
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How did Becquerel discover radioactivity? |
- Exposed to sunlight: investigated how uranium emits light (phosphoresces) - Observed 'invisible rays' emitted by uranium expose (darken) photographic plates: radiation emitted by uranium didn't need external energy source - Radioactivity discovered |
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How did Becquerel show that this type of radiation can ionise gases? |
His skin burned after leaving radium in his pocket - didn't realise ionisation could occur in cells was the cause of the damage. |
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In 1920, what did scientists to the effects of ionising radiation? |
Cancer and other health problems. |
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What damage can large amounts of ionising radiation do? |
- Tissue damage e.g. reddened skin (radiation burns) - Effects that can't be seen |
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What damage can smaller amounts of ionising radiation do over long periods of time? |
- Damages to the DNA inside a cell: cell mutation - Therefore, cancer |
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List four precautions to take to protect yourself from radiation when working with radioactive materials and why you must do this. |
1. Wear protective clothing - no direct exposure, less risk of radiation burns 2. Handle radioactive sources with tongs to maximise the distance from the source - decreases risk 3. Don't point radioactive sources at others - maximise space between them 4. Keep radioactive sources in a lead-lined container - most penetrating radiation can be stopped with a few mm of lead |
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What uses to gamma rays have? |
- Diagnosis of cancer - Treatment of cancer - Sterilisation of equipment - Irradiating food - Finding leaks in water pipes |
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How can gamma rays be used to diagnose cancer? |
- Tracer solution containing gamma rays injected into body - Tracer collects in areas of abnormal activity e.g. cancers - Gamma rays detected using 'gamma camera' |
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Why are gamma sources used to diagnose cancer? |
They pass straight through the body, allowing them to be detected. |
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How can gamma rays be used to treat cancer i.e. radiotherapy? |
- Gamma rays can be used as beams of radiation to target and kill cancer cells - Radioactive sources can also be put inside a person for a limited amount of time at the place where the cancer is |
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How can gamma rays be used to sterilise equipment? Why? |
- They're usually heated, but some instruments e.g. plastic syringes can't be sterilised with heat, so they're irradiated with gamma rays. - They need to be sterilised to kill microorganisms before using them on patients |
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Why are gamma rays be used to irradiate food? How? Is it dangerous? |
- All food contains bacteria, which can eventually cause food to decompose. Certain types of bacteria can cause food poisoning - Gamma rays kill bacteria by irradiating the food - This makes it safer to eat and can be stored longer before going off and can kill any pests e.g. insects in it - This doesn't make it more radioactive |
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List five examples of food in the UK that can be irradiated. |
Fruit Vegetables Cereals Bulbs (e.g. onions) Shellfish |
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How can alpha particles be used in smoke alarms? |
- Smoke alarms contain isotopes (americium-241) - Between two electrically charged plates, there's an electrical circuit with an air gap - Americium-241 source releases alpha particles, which ionise the air to give electrons and ions - The charged particles are attracted to opposite charged plates, allowing a small electrical current to flow - Air constantly being ionised by americium-241 source, meaning there's a constant electric current. While current flows, alarm won't sound - When smoke gets between gap, smoke particles absorb alpha particles, decreasing current flowing - Alarm goes when the current goes down below a certain level |
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How can beta particles be used in checking paper thicknesses? |
- Paper thickness is changed by squeezing wood pulp between rollers with different forces - Detectors count the rate beta particles get through the paper from a source on one side - Too thin? Beta particles penetrate paper and detector records a higher count rate. Computer senses a higher count rate and reduces pressure to make it thicker - Too thick? Opposite happens |
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How can gamma rays be used to detect leaks in water pipes? |
- Gamma source added to water detects leaks in pipes underground e.g. water pipes - If there's a leak, water leaks to surrounding earth. GM tube following the path of the pipe detects higher radiation levels where there's a leak |
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Define radioactive decay. |
The break up of unstable nuclei. When it decays, it gives out radiation - alpha, beta or gamma. |
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What type of process is radioactive decay? |
A random process. |
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TRUE OR FALSE Some types of nueclei are more unstable than others and decay at a faster rate. |
TRUE |
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Define half life. |
The time it takes for the radioactivity of a sample to fall by half a.k.a the time for half the nuclei to decay. |
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What is background radiation? |
Low level ionising radiation from space and naturally radioactive substances in the environment. |
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What is the 'background count'? |
The average of several readings of the radioactivity of a source. |
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How do you work out the corrected reading of a source's activity? |
You subtract the background count from the measurements. |
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What is the main source of background radiation in the UK? |
Radon gas |
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How is radon gas formed? |
When uranium in rocks decays, it produces other radioactive isotopes that also decays, one of these being a gas called radon. |
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How can radon gas build up in houses? |
Radon diffuses into the air from rocks and soil and builds up in houses, especially ones with poor ventilation. |
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How long is the half-life of radon? |
3.8 days |
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How does radon decay? |
By giving out an alpha particle |
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What does the amount of radon in the air depend upon? |
The type of rock and its uranium content. |
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List seven sources of background radiation and how much percentage they are within the amount of BR in the UK. |
- Radon gas (50%) - Ground and buildings (14%) - Medical (14%) - Nuclear power (0.3%) - Food and drink (11.5%) - Cosmic rays (10%) - Other (0.2%) |
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What are cosmic rays? |
High-energy charged particles streaming out of the Sun and other stars, as well as supernovae, neutron stars and black holes. They're a form of ionising radiation. |
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What stops most cosmic rays from entering the Earth? |
The upper at.mosphere |
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How is the radioactivity of a source measured? |
Using a Geiger-Muller (GM) tube A GM tube can be connected to a counter or it may click each time ionising radiation is detected. |
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What is the count rate of of radioactivity's measurement in a GM tube? |
Number of clicks per second or per minute |
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What can you work out from a GM tube's measurements, other than the radioactivity of a source? |
How long it takes the count rate to halve from a graph. |
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How do you work out the half-life of a substance based on a graph of the count rate against time for a radioactive source? |
1. Find one count rate e.g. at 600 counts/second, it was at 5 mins 2. Find out what half of the first count/second measurement - 600/2 = 300 3. See what minute corresponds with 300 counts/second - e.g. 12 mins 4. Subtract the first time from the second - e.g. 12 - 5 = 7 mins 5. The answer (e.g. 7 mins) is the half-life |
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What do crumple zones do? |
Reduce the momentum of a moving object (e.g. car) over a longer period of time |
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How can crumple zones be used in cars? |
As airbags They reduce the momentum of the car over a longer time period, thus meaning that the deceleration of the people in the car is less in a crash, resulting in less force on them and reducing the risk of seat belt injury |
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What do seat belts do? |
Reduce the rate of change of momentum, resulting in less force on passengers |
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Equation for force needed to change momentum of an object |
Force = change in momentum/time F = (mv-mu)/t N = (kg/ms)/s |
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Equation for work done stopping a vehicle |
Work done = braking force X braking distance |
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What is the equality of work done? |
Work done = initial kinetic energy |
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What happens to the kinetic energy when a moving object has been stopped? |
All kinetic energy has been removed |
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Define gravitational potential energy (GPE) |
Energy in anything on Earth that can fall Work done against gravity in moving an object of mass up to a height |
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Why does a vehicle with more speed require more time to break? |
There's more kinetic energy to be removed, so it takes longer to do so |
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How can friction be useful in safety in driving? |
Friction allows brakes to slow the vehicle down |
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List the 5 steps of a skydiver reaching terminal velocity |
1. Skydiver drops: large acceleration, small air resistance 2. Skydiver falling: large acceleration, medium air resistance 3. Skydiver falling - forces balance: large acceleration, large air resistance (terminal velocity) 4. Parachute opens: air resistance increases 5. Falling with parachute: Air resistance decreases again to balance weight (new terminal velocity) |
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What is the gravitational field strength (GFS) of Earth? |
10N/kg |
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What does the GFS of Earth mean? |
Each kg is pulled down with a force of 10N |
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Describe in 2 steps how a rocket flies |
1. Thrust from rocket pushes down on gases 2. Thrust from gases pushes rocket up |
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TRUE OR FALSE: If the same force is put on 2 different sized objects, the smaller one accelerates less |
FALSE The smaller one accelerates more |
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How would you ensure that 2 objects of different sizes had equal acceleration? |
A larger force must be applied to the larger object |
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Equation for weight |
Weight = mass X GFS N = kg X N/kg N = kg X m/s^2^ |
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List the 4 steps of converting thermal energy to electrical energy |
1. Thermal energy from the core transferred to a coolant (usually water at a high pressure), which is pumped through a reactor 2. This super-heated water is pumped to a 'heat exchanger', which is used to produce steam 3. Steam drives a turbine, which turns a generator 4. Generator transfers kinetic energy into electrical energy |
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What's one problem with using a nuclear reactor core to obtain nuclear power? |
Radioactive waste builds up in the reactor core |
