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
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
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
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
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
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
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
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)
- 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.
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