Definitions
the ability to do work (ability to make something observable happen)
energy
potential energy of an object elevated above the ground
gravitational potential energy
energy possessed by objects that are moving
kinetic energy
If 80 J of electrical energy are input to power a Playstation 4, the output of energy is
80J
microwave
input: electrical
output: heat
"stored" energy
potential energy
energy stored by an object that is stretched or squashed
elastic potential energy
energy that causes objects to gain temperature
heat energy
A bulb has 100 J input and 70 J useful light.
How much energy is wasted?
30 J
television
input: electrical
output: light, sound
energy due to the motion of an object
kinetic energy
energy that is released when chemical react together
chemical potential energy
free points!
free points!
A machine is 50% efficient.
If it gets 200 J input, how much is useful?
100 J
hair dryer
input: electrical
output: thermal, kinetic (air)
law that states that energy cannot be made or lost
Law of Conservation of Energy
energy released from the movement of charged particles
electrical potential energy
energy that might be released when object gets hot; moves in small packets of energy called photons
light energy
A machine is 80% efficient.
Is 20% useful or wasted?
wasted
stovetop
input: electrical
output: thermal
a measure of an object's ability to provide useful energy
energy efficiency
energy stored in the nucleus of atoms that can release energy slowly or quickly
nuclear potential energy
energy carried by air and detected by the ear
sound energy
A heater is 90% efficient.
Out of 100 J input, how much is wasted?
10 J
solar panel
input: light
output: electrical