# 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

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good but no detailed explanation

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