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69 Cards in this Set
- Front
- Back
What does the gradient of the line on a distance-time graph represent? |
An objects speed. |
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Definition of velocity. |
Speed in a given direction. |
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How do you work out acceleration? |
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What does the area under the line on a velocity time graph represent? |
The distance travelled in a given time. |
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Definition of acceleration. |
The change of velocity in a given direction. |
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Unit of force. |
Newton. |
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What is a resultant force? |
The overall force. |
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Factors stopping stopping distance. |
Tiredness, alcohol, drugs, mobile phones, adverse road conditions, poorly maintained vehicles and if the vehicle is travelling quickly. |
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Equation for stopping distance. |
stopping distance = thinking distance + breaking distance |
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What is terminal velocity? |
Equal forces acting on an object, meaning it can no longer travel any faster. |
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What is Hooke's Law? |
The extension of a spring is directly proportional to the force applied, provided its limit of proportionality is not exceeded. |
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Definition of work done. |
Energy transferred. Work is done when a force makes an object move. |
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What is gravitational potential energy? |
Energy stored in an object because of its position in the Earth's gravitational field. |
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What is momentum? |
The product of moving objects. |
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What is conservation of momentum? |
Total momentum stays the same. |
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What happens to the momentum in an explosion? |
When two objects push each other apart, they move apart: |
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What is a crumple zone? |
An area of a car that is designed to fold in a collision. This increases the impact time so reduces the force on the car and then people in it. |
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What happens when two vehicles collide? |
- They exert equal and opposite forces on each other |
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What do seat belts and air bags do to forces in a crash? |
They spread the force out over the biggest area of the body, the chest, to reduce the impact of these forces. |
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How do you reduce impact force? |
- Increase distance |
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What was the universe before galaxies and stars formed? |
Floating matter of hydrogen and helium. |
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How are galaxies and stars formed? |
By gravity pulling the matter together. (Hydrogen and helium) |
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What is a protostar? |
A dense ball of hot gas and dust that can go on to develop a star. |
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Life cycle of a low mass star. |
Protostar - main sequence star - red giant - white dwarf, black dwarf. |
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Life cycle of a high mass star. |
Protostar - main sequence star - red supergiant - supernova - neutron star - black hole. |
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How are light elements formed? |
Inside the stars as a result of nuclear fusion. |
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How are heavy elements formed? |
In supernovas. |
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How was the sun and the rest of the solar system formed? |
From the debris of a supernova. |
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Why does your hair stand up with you touch a Van de Graff generator? |
Because the electrons are trying to escape and your hair is the easiest way to get out if you're stood on a plastic box, otherwise the electrons will just escape to the ground. |
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Circuit symbol for bulb. |
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Circuit symbol for switch. |
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Circuit symbol for voltmeter. |
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Circuit symbol for ammeter. |
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Circuit symbol for battery. |
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Circuit symbol for cell. |
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Circuit symbol for resistor. |
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Circuit symbol for variable resistor. |
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Circuit symbol for diode. |
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Circuit symbol for thermistor. |
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Circuit symbol for fuse. |
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Circuit symbol for LDR resistor. |
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Definition of current. |
Flow of charged particles. (electrons) |
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What is a parallel circuit? |
The current has a choice of roots. The current will go down the easiest path, it may split at a junction. |
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What is a series circuit? |
There is the same current through each component. |
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What is resistance? |
Anything that will resist a current. Its measured in Ohms. |
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Resistance rules for series circuits. |
Total resistance = resistance one + resistance two + resistance three... |
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Resistance rules for parallel circuits. |
1/total resistance = 1/resistance one + 1/resistance two + 1/resistance three... |
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What is a a.c current? |
A current which is constantly changing direction. It flows one way, then reverses its direction. This is in cycles. |
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What is a d.c current? |
The current passes in one direction. This is direct from a battery or cell. |
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What is mains electricity supply? |
a.c |
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What colour is the earth wire? |
Green and yellow. |
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What is the brown wire on a three pin plug? |
Live wire. |
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What is the blue wire on a three pin plug? |
Neutral wire. |
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What is a fuse? |
A thin wire that heats up and melts if too much current passes through. |
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What is a circuit breaker? |
Can be used in place of a fuse. There is a switch that opens and cuts off the supply if the current is bigger than a certain value. It 'trips'. |
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What are the three main types of radiation? |
Alpha, Beta and Gamma radiation. |
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What is background radiation? |
Radiation that is around us all the time. This can be from radioactive substances in the environment, x rays, from space. |
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In alpha decay, what happens to the nucleus? What particle is emitted? |
The nucleus loses 2 protons and 2 neutrons. These are emitted as alpha particles. |
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In beta decay, what happens to the nucleus? What particle is emitted? |
A neutron changes into a proton and an electron. The electron is emitted as a beta particle. |
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How is a alpha particle represented? |
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How is a beta particle represented? |
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What is alpha radiation stopped by? |
Paper or a few centimetres of air. |
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What is beta radiation stopped by? |
Thin metal or about a metre of air. |
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What is gamma radiation stopped by? |
Thick lead and unlimited range in air. |
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When is a gamma (y) particle emitted? |
After an alpha or beta particle has been emitted. Its uncharged and has no mass. |
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How do you work out the half life? |
Half the largest number produced. |
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Name one way alpha, beta and gamma radiation can be used in industry. |
Alpha - used in smoke alarms. |
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What is Nuclear Fission? |
Occurs in Uranium 235/Plutonium 239. The splitting of an atomic nucleus. This releases three neutrons. These go on to strike more uranium atoms. This is a chain reaction. |
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What is Nuclear Fusion? |
Forcing two nuclei close enough together so they form a single larger nucleus. Two protons collide, one turns into a neutron (1). Two more protons collide separately with these (1) atoms. It produces helium which is now useless, but the energy it produces is not useless. |