Physics revision-energy

elastic potential energy=0.5×spring constant×[extension]2

Ee=0.5×K×e2

(J)=(no unit)×(N/M)×(M)

stored energy in squashed or stretched objects

stored energy in raised objects

gravitational potentail energy=mass×gravitational field strength×height

Ep=m×g×h

Kinetic energy is movement energy

Kinetic energy=1/2 × mass × speed2

• Energy can transfer or move from one store to another in different ways. Devices such as lamps and heaters may be involved or processes such as combustion.
• Energy can be transferred by:

Heating-energy is transferred from the hotter object to the cooler one.

Mechanical transfer-energy is transferred by the movements of parts in a machine

Electrically-when an electric current is complete

Radiation-carried by waves

Energy is always conserved

• Carrry transverse vibrations in electrical and magnetic fields,not vibrating particles.
• Do not need matter to travel through-can travel through a vacuum
• In a vacuum, all waves travel at approximately 3×10"2 m/s- the fastest speed possible.
• When the waves travel through matter, the travel a bit slower than this but less than 1/2 as fast in a vacuum.

wave speed=frequency×wavelength

v=f×lamda 

(m/s)=(Hz)×(M)