Gcse physics

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John

Cards (879)

Energy is never created or destroyed, it's only ever transferred between different forms and objects
Forms of energy 
Thermal or internal energy
Kinetic energy
Gravitational potential energy
Elastic potential energy
Chemical energy
Magnetic energy
Electrostatic energy
Nuclear energy
Energy stores 
They are not fixed, energy can be transferred between them
Transferring energy between forms
1. Mechanically
2. Electrically
3. By heating
4. By radiation like light or sound waves
System 
The collection of matter that we are considering
Open system 
Can exchange energy with the outside world
Closed system 
Separate from the outside world, so neither matter nor energy can enter or leave
Energy transfer in a kettle 
1. Electrical energy from the plug socket flows to the heating element
2. Heating element transfers energy to the water's thermal energy store
Work done 
Another way of saying energy transferred
Types of work done
Mechanical
Electrical
Mechanical work done 
Using a force to move an object
Electrical work done 
Energy required to overcome resistance in wires of a circuit
Braking a train 
Friction between brakes and wheels causes energy in the wheel's kinetic energy stores to be transferred to the thermal energy stores of the surroundings
Kinetic energy 
The energy that an object possesses due to its motion
Kinetic energy 
Depends on an object's speed
Depends on an object's mass
Faster an object is moving
More kinetic energy it will have
More mass an object has
More kinetic energy it will have
E_k stands for kinetic energy
m stands for mass, measured in kilograms
v stands for velocity, measured in meters per second
Conservation of energy principle 
Energy can be transferred, usefully stored or dissipated, but can never be created or destroyed
Energy can only move between different objects and different forms
Charging a phone 
1. Electrical energy from the main supply travels along the wire
2. Gets transferred to the chemical energy store in the phone's battery
Using a charged phone
1. Chemical energy is converted back to electrical energy
2. Electrical energy flows around the circuit and powers the different parts like the screen and the speaker
Energy transfer in a phone 
1. Electrical energy is converted to light energy in the screen
2. Electrical energy is converted to sound energy in the speaker
Some energy is dissipated as wasted energy, generally in the form of heat
System 
A portion of the physical universe that you've chosen to analyze
Open system 
Energy and matter can freely move between the system and the environment
Closed system 
Energy and matter can't enter or escape the system
In a closed system, the overall energy doesn't ever change
Conservation of energy principle 
Energy can be transferred, usefully stored or dissipated, but can never be created or destroyed
Energy can only move between different objects and different forms
Charging a phone 
1. Electrical energy from the main supply travels along the wire
2. Gets transferred to the chemical energy store in the phone's battery
Using a charged phone
1. Chemical energy is converted back to electrical energy
2. Electrical energy flows around the circuit and powers the different parts like the screen and the speaker
3. In the screen, electrical energy is converted to light energy
4. At the speaker, electrical energy is converted to sound energy
Some energy is dissipated as wasted energy, generally in the form of heat
System 
A portion of the physical universe that you've chosen to analyze
Environment 
Everything outside the system
Open system 
Energy and matter can freely move between the system and the environment
Closed system 
Energy and matter can't enter or escape the system
In a closed system, the overall energy doesn't ever change