Meters per second, m/s

The speed

The object is not moving

The object is moving at a constant speed

The object is accelerating

It must specify a direction.

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Meters per second, m/s (the same as speed)

Meters per second squared, m/s^2

The rate if acceleration

The object is traveling at a steady speed.

The object has a constant rate if acceleration or deceleration

The rate if acceleration is increasing (or decreasing).

The distance travelled

Newtons

Equal and opposite forces on each other.

The table exerts an equal upwards force on the book.

An object generally has lots of different forces acting on it at the same time.

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The object remains stationary

The object will continue to move at the same steady speed in the same direction.

The object will accelerate in the direction of the resultant force.

If the force is in the same direction that the object is moving, the object will accelerate.

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The faster the car, the greater forwards force it has, meaning that a larger deceleration is required.

Thinking distance and braking distance.

The distance a car travels between the driver noticing the stimulus and applying the brakes.

Driver being drunk, tired or under the influence of drugs.

The distance a car travels between application of brakes and coming to a complete stop.

Poorly maintained roads

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A resultant force must be acting on it.

Gravity

The amount a falling object accelerates due to the force of gravity.

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Newtons per kilogram, N/kg.

An object falls through a fluid (liquid/gas).

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Make vehicle more streamlined > reduces air resistance > less fuel required to move it.

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The increase in an object's length from its original length when a stretching force is applied to it.

Will return to its original shape after being deformed.

Extension is directly proportional to the force applied, providing the limit of proportionality is not exceeded.

The maximum force that can be applied to an elastic object before it will not return to its original shape after being deformed.

When an object is stretched, work is done.

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A force must be being applied to it.

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The energy stored in an object because of its position in the Earth's gravitational field.

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The rate of energy transfer (in Joules per second).

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Watts, W

Greater mass

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Kilogram-meters per second, kgm/s.

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When objects interact (collide), the total momentum before (as they move towards each other) is equal to the total momentum after (as they bounce apart/move off together).

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- shorter impact time

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Areas manufactured at the front and rear of cars, designed to fold up in a collision.

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A poor conductor of electricity

Two insulators are rubbed together

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Required to push electrons around a complete circuit

Two or more cells

Enables the current to be broken

Emits light as a sign that current is passing through/as a source of light.

Only allows current through in one direction

Only allows current through in one direction AND emits light when a current passes through

Measures electrical current through a component

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Limits the current in the circuit

Allows the current in the circuit ti be varied

Contains a wire of specific thickness which melts if to great a current flows through, breaking the circuit. A safety feature, e.g. to prevent surges.

Transfers electrical energy to thermal energy, heating the surroundings

Measures potential difference across a component

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The rate of flow of charge (unit: Coulombs) past a point.

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The amount of energy transferred to a component (or work done on a component) per coulomb of charge flowing though it.

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The opposition to the flow of current.

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More energy is transferred to the component = greater resistance.

Less energy transferred to the component = lower resistance.

The current through a component/resistor is directly proportional to the potential difference across it (if the resistor is kept at a constant temperature).

Increase current > temperature increases > resistance increases.

Brighter light = lower resistance

Higher temperature = lower resistance (opposite to all other resistors).

All components are connected one after the other.

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Current is the same through all components (because there is no choice of route for charge).

The potential differences of all components in the circuit add up to the potential difference of the supply.

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The resistances all components in the circuit add up to the total resistance of the circuit.

Components are connected across the supply, creating separate loops.

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Different amounts of current can flow through different components (because there are junctions in the circuit).

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Every component's potential difference is the same (because they are all connected across the supply p.d.).

Greater resistance = less current

Supplied by cells and batteries.

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Supplied by the mains.

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How many full wavelengths pass a point in one second.

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50 Hz; changes direction 50 times per second.

Between +325 and -325 volts

230 Volts

Brown, goes to the right

Green and yellow stripy, in the middle

Blue, goes to left

If live wire touches the appliance's metal case, it could give you an

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The appliance is double-insulated

An electromagnetic switch which cuts off the supply if the current exceeds a certain value

A "residual current circuit breaker".

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Unstable

Radioactive decay, where it emits radiation and turns into another elements.

Unpredictable and random

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Is around us all the time

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When nuclear radiation passes through a material and collides with its atoms, knocking off electrons. This makes the atoms ions.

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The nucleus emits an alpha particle. Its mass number decreases by 4.

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2 protons and 2 neutrons

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They are relatively large, so have lots of collisions with the atoms of the material they pass through.

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- sheet of paper

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Smoke alarms

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A neutron in the nucleus changes into an electron and a proton. The electron is emitted from the nucleus.

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One high speed electron

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They are much smaller and faster than alpha particles, so have fewer collisions with the atoms of the material they pass through.

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- thin sheet of aluminium

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Monitoring thickness of paper/foil by measuring how much radiation passes through.

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The nucleus emits an electromagnetic wave

Have no mass and no charge, so there is no change in mass number or atomic number.

Rays can travel very deep into a material before hitting an atom.

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- several centimeters of lead

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Tracers in medicine. Swallowed and external detector tracks progress through body.

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Believed that the atom is a sphere of positive charge with negative electrons stuck in.

They fired alpha particles at a thin sheet of gold foil.

Most alpha particles passed straight through the foil.

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Some alpha particles were deflected through small angles.

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A few alpha particles rebounded through very large angles.

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The number of nuclei that decay per second.

More reactive material.

The time taken for the number of unstable nuclei in the sample to halve.

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Finds age of ancient objects

Finds age of organic material e.g. Wood

Finds age of igneous rocks

Uranium-235 and Plutonium-239

Neutron fired at nucleus > nucleus absorbs neutron > nucleus splits into 2 or 3 smaller nuclei > 2 or 3 neutrons are released > lots of energy released (much more than burning fossil fuels) > neutrons released can hit other nuclei and start a chain reaction!!! Has to be carefully controlled.

Forcing two nuclei together by making them collide at very high speed so they form a single larger nucleus.

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Nuclei are positively charged > repel each other > requires huge amounts of energy to force them together > need to be heated to enormous temperatures > has to be contained in a magnetic field.

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- radon gas, seeping through ground from radioactive substances in rocks underground. Alpha particles, health hazard if inhaled.

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Re-used, but leftover radioactive waste has to be stored in secure conditions for many years to stop it contaminating the environment.

- keep as far away from sources as possible

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Created by the Big Bang

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The Universe was a hot glowing ball of radiation. The nuclei of the lightest elements formed.

The Universe expanded and cooled. Uncharged atoms were formed.

A dark patchy cloud of hydrogen and helium. Dust and gas was pulled together by gravity to form stars.

Intense heat. It was hot enough to start nuclear fusion. Stars began to emit visible light and other radiation.

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Cloud of dust and gas > pulled together by gravity > forms a PROTOSTAR > becomes denser > hydrogen and other light elements start nuclear fusion > energy released > star gets hotter and brighter > outward force of radiation is equal to inward force of gravity > star is stable. MAIN SEQUENCE STAR.

Runs out of hydrogen nuclei > unbalanced forces pull star in so fast that temperature rockets > star expands and cools > RED GIANT > helium and other light elements fuse to form heavier elements > fusion stops > star contracts > WHITE DWARF > no more light emitted > star becomes denser > BLACK DWARF.

Runs out of hydrogen nuclei > unbalanced forces pull star in so fast that temperature rockets > star expands and cools > RED SUPERGIANT > collapses > explodes > SUPERNOVA > outer layers thrown out into space > core remains > NEUTRON STAR (very very dense) > if neutron star is big enough it becomes a BLACK HOLE (gravity so strong not even light can escape).

By fusion processes in stars.

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In the final stages of a massive star's life when there is enough energy. Then they are distributed through space by the supernova explosion.

Heavier elements than iron are present in the sun and planets.