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Physics - P1 - Energy, Key: - Coggle Diagram
Physics - P1 - Energy
Energy changes in a system, and the ways energy is stored before and after such changes
Energy changes in systems
change in thermal energy = mass × specific heat capacity × temperature change
The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius
Changes in energy
kinetic energy = 0.5 x mass x (speed)2
elastic potential energy = 0.5 x spring constant x (extension)2
gravitational potential energy = mass x gravitational field strength x height
Energy stores and systems
There are changes in the way energy is stored when a system
changes
A system is an object or group of objects
Power
Power is defined as the rate at which energy is transferred or the
rate at which work is done
Power = energy transferred / time
power = work done / time
An energy transfer of 1 joule per second is equal to a power of 1
watt
National and global energy resources
The main energy resources available for use on Earth include: fossil
fuels (coal, oil and gas), nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, the tides, the Sun and water waves
A renewable energy resource is one that is being (or can be)
replenished as it is used
The uses of energy resources include: transport, electricity
generation and heating
Conservation and dissipation of energy
Energy transfers in a system
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed
where there are energy transfers in a closed system, there is no net change to the total energy
was to reduce unwanted energy transfers: through lubrication and the use of thermal insulation
The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material.
Efficiency
efficiency = useful output energy transfer
/ total input energy transfer
efficiency = useful power output
/ total power input
Key:
Major focus of exam
Small part of exam