Energy
Types of energy
Kinetic energy - energy of a moving object
Kinetic energy = 1/2mv2
Gravitational potential energy (g.p.e.) - energy of an object being raised up against gravity
gain/lose in g.p.e. = mgh
Chemical energy - stored in chemical substance, released in chemical reaction
Elastic Strain energy - energy when open object is being stretched or compressed
Nuclear energy - energy stored in the nucleus of an atom, ex: all radioactive material
Internal energy - total kinetic and potential energies of an object’s particle, energy stored in hot object
Thermal energy - energy being transferred due to the difference in temperature, energy spreading out
from hot object
Energy transfers
● By force.
○ Lifting something- give it g.p.e.
○ Moving something- give it kinetic energy
● By heating
○ Thermal energy spread out from hot objects
● By radiation
○ Light from the Sun to Earth, transferred as infrared, ultraviolet radiation
● By electricity
○ Transferred by heating and waves
Energy conservation
In any energy conservation, the total amount of energy
before and after conservation is constant.
Energy efficiency -fraction of the energy that ends up in the desired form.
No system is perfect. Whenever there is a change in a system, energy is transferred and some of that
energy is dissipated ( wasted ).
Efficiency = useful energy out put x 100% Efficiency = useful power out put x 100%
energy input power in put
Types of energy
Kinetic energy - energy of a moving object
Kinetic energy = 1/2mv2
Gravitational potential energy (g.p.e.) - energy of an object being raised up against gravity
gain/lose in g.p.e. = mgh
Chemical energy - stored in chemical substance, released in chemical reaction
Elastic Strain energy - energy when open object is being stretched or compressed
Nuclear energy - energy stored in the nucleus of an atom, ex: all radioactive material
Internal energy - total kinetic and potential energies of an object’s particle, energy stored in hot object
Thermal energy - energy being transferred due to the difference in temperature, energy spreading out
from hot object
Energy transfers
● By force.
○ Lifting something- give it g.p.e.
○ Moving something- give it kinetic energy
● By heating
○ Thermal energy spread out from hot objects
● By radiation
○ Light from the Sun to Earth, transferred as infrared, ultraviolet radiation
● By electricity
○ Transferred by heating and waves
Energy conservation
In any energy conservation, the total amount of energy
before and after conservation is constant.
Energy efficiency -fraction of the energy that ends up in the desired form.
No system is perfect. Whenever there is a change in a system, energy is transferred and some of that
energy is dissipated ( wasted ).
Efficiency = useful energy out put x 100% Efficiency = useful power out put x 100%
energy input power in put
