The energy of an object due to it's
position. Affected by gravity, height and mass
Elastic potential energy
The energy stored in a sprringy object
when we stretch or squash it
Can be transferred from one form to another
E.g. a torch
The battery pushes a current through the bulb making the torch bulb
emit light and it also gets hot. We can show the energy transfers using a
flow diagram
E.g. an falling block
Has gravitational energy
Transferred to kinetic as it falls and speeds up
Transferred into heat and sound when it
hits the ground
Conservation of energy
Scientists have found that the
total energy after a transfer is
the same as the energy before
the transfer
This is known as the conservation of energy
It tells us that energy cannot be created nor destroyed
Useful energy
Many things use energy such as machines
but energy is wasted. It is not 100% effecient
In a washing machine the friction between the
moving parts causes some of them to heat up. This is
wasted energy
Useful Energy
The energy transferred to where it is wanted,
in the form it is wanted
Wasted Energy
Energy that is not usefully transferred
Spreading out
Wasted energy is dissipated to the surroundings
Useful energy eventually transfers to the surroundings too
E.g. tyres
Energy becomes less useful, the more it dissipates
Energy and efficiency
Weight is measured in newtons (N). THe weight of a
1kg object on the Earth's surface is about 10N
Energy is measured in joules (J). The energy needed to lift a weight of 1N by a height of metre
Sankey Diagrams
Used to represent effeciency
Efficiency = (Useful energy transferred by the device /
total energy supplied the the device) x 100%
Improving efficiency
Efficiency can be imrpoved in a number of
ways depending on the source of the
energy waste. This can save money and
time.
e.g. friction between the moving pasts
causes heating -> Lubricate the moving
parts to reduce friction