Energy Changes

Cards (9)

State the law of energy conservation
Energy cannot be created or destroyed, only transferred
Describe the energy changes that occur in a filament light-bulb.
Electrical energy is transferred into light and heat energy.
Energy transfers for a bungee jumper
GPE to KE when falling, KE to EPE as cord tightens, lowest point in total GPE = EPE
Why does bungee jumper slow down as the cord begins to stretch?
Kinetic energy decreases since it is converted to EPE, and as it is proportional to velocity squared, speed also decreases
Energy changes in a power station
Heat energy released heated water to make steam which moves the turbine, converting to kinetic energy that turns the generator, electrical energy generated by the generator
In what ways can the energy of a system be changed?
Through work done by forces, through electrical input, through heating
How can energy be changed through work done by forces?
A force which moves an object (kinetic energy) causes work to be done over distance.
Work done (J) =
force (N) x distance (m)
W = Fd
Why do wasteful mechanical processes cause a rise in the temperature of the surroundings?
They causes energy to be transferred by heating the surroundings.