GCSE Physics-Roller Coasters and Relativity

These Revision cards are for AQA Extra science physics examinations.

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  • Created by: Georgia
  • Created on: 12-11-09 20:05

Work

When a Force moves an object, energy is transfered and work is done

  • When something moves, something else is providing some sort of effort.
  • The item putting in the effort need a supply of energy (eg. fuel or food)
  • The object then does work by moving the object, this involves the transfer of energy into other forms
  • -
  • Work done can be useful (eg. lifting a load) or useless (eg. energy loss through friction)

Work Done = Force x Distance

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Kinetic Energy

Anything which moves has Kinetic Energy

Kinetic Energy = 1/2 x mass x velocity (squared)

Kinetic Energy Depends on-

  • mass-the heavier it is the more kinetic energy it has
  • -
  • speed-faster speed, higher kinetic energy
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Electrical Energy

Anything which supplies electricity is also supplying electrical energy

  • When an electrical charge goes through a change in voltage, energy is transfered
  • Energy is supplied to the charge at the power source to raise the voltage
  • The charge gives up this energy when it passes through components in the circuit.

Electrical energy = Voltage x Current x Time

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Potential Energy

Potential Energy is the energy an object potentialy has

Potential Energy = mass x Gravity x hieght

  • The gravity on earth is aproximatly 10m/s(squared)
  • If an object has no hieght, there is no potential Energy
  • On diffeent planets the gravity changes
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Conservation of Energy

There are 2 types of energy Conservation

  • "Energy Conservation" is all about using less fossil fuels because they might run out and they damage the enviroment
  • "Principle of Energy Conservation" This is the principle that states all the workings of the entire universe
  • The principle energy states that energy can not be created of destroyed. Energy is only useful when it is converted from one form top another
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Speed of Falling Objects

When something Falls, Potential Energy is converted to Kinetic Energy

The further it falls, more kinetic Energy

Kinetic Energyu Gained = Potential Energy Lost

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Power

Power = work done / time taken

Power is the ampount of energy transfered in a space of time.

Power is not how strong a force is or energy

Power is measured in Watts of Joules

Power = Energy Transfered / Time Taken

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Circular Motion and Centripetal Force

In Curcular Motion, Velocity is Constantly Changing

The force is to the centre of the circle, the velocity goes off in a strait line.

Different Forces can cause curcular Motion-friction, tension, gravity.

Centripetral Force (N) = (Mass(kg) x speed(squared) ) / Radius (m)

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Roller Coasters

  • At the top of the ride there is lots of Gravitational Potential Energy
  • As the carrige goes down a slopethere is kinetic energy and the carrige speeds up.
  • When it goes uphill the roller coaster looses kinetic energy and gains potential energy.

Loop the Loop

  • Loop the loop requires centripal force
  • In a loop the loop, forces acting on you are wieght(down) and a reaction force(to the centre of the circle)
  • At the top of the loop, wieght and reaction force are in the same direction-thi smakes you feel light
  • At the bottomthe forces are in opposite directions making you feel heavier

When designing rollercoasters safety (headrests and seatbelts) and social effects (jobs, traffic, noise) must be considered.

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Einstein's Relativity

Theries can develop in 2 ways, good theories can always be tested

  • Experimental results
  • Reasonong and creative thinking
  • Einstiens theory of relativity was published in 1905
  • Einstiens theory is based on assumptions such as speed of light is always the same
  • The ideas were developed through thought experiments-using hypothetical problems
  • When published, the theory was very radical, he said time and space are not fixed, they can bend or stretch
  • This theory was hard to accept at the time as it contradicted newtons laws of motion
  • In 1915, he extended his ideas to say gravity can bend light
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Comments

Berny

good but no detailed explanation

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