Chapter 1- Energy transfers and efficiency Flashcards
(34 cards)
Kinetic Energy
Energy in a moving object- aka movement energy
Heat energy
Aka thermal energy
Light
Aka radiant energy
Gravitational potential energy
Energy stored in raised objects
Chemical
Stored energy in fuels, batteries and foods
Sound
Energy released from vibrating objects
Electrical
Energy in moving charges or static electric charges
Elastic potential
Stored energy in stretched or squashed objects
Nuclear
Stored in the nuclei of atoms
Internal energy
Contained in a thermodynamic system
Strain energy
Released when atoms in a molecule rearrange themselves in a chemical reaction
Energy transfers
Different forms of energy can be transformed from one form to another.
Sankey diagrams
Sankey diagrams summarise all the energy transfers taking place in a process. The thicker the line or arrow, the greater the amount of energy involved.
Conservation of energy
Energy can be transferred usefully, stored or dissipitated. It cannot be created or destroyed.
Efficiency
The efficiency of a device is the proportion of the energy supplied that is transferred in useful ways
Calculating efficiency
The efficiency of a device can be calculated
Efficiency= useful energy out divided by total energy in (for a decimal efficiency)
Or
Efficiency= (useful energy out divided divided by total energy in) x 100 ( for % efficiency)
Can energy be created, destroyed or converted?
Energy can only be converted into another form. It cannot ever be created or destroyed. This is called the conservation of energy.
Name 10 types of energy
Light Thermal Internal Sound Elastic potential Electric potential Kinetic energy Chemical potential Nuclear potential Gravitational potential
Units of energy
Joules (J)
Energy is conserved
Energy cannot be made or created, destroyed, lost or disappear
It can be only transformed from one type to the other
Power
Calculates the amount of energy delivered per second
Calculating power
Power= energy divided by time P= E/t
Units of power
Watts (W) energy must be in joules and time in seconds
Work done
A measure of energy