Kinetic
Energy
Kinetic energy (abbreviated to
KE below - but don't you dare do that in an exam paper!) is the energy
of motion or movement energy.
There are three forms of KE
- vibrational (the energy due
to vibrational motion),
- rotational (the energy due to
rotational motion), and
- translational (the energy due
to motion from one location to another).
Generally at KS3 and 4 we consider
translational kinetic energy when we look at kinetic energy
The Translational Kinetic Energy
(you can just call it kinetic energy!) of an object depends on how fast
the object is moving, the faster it goes the higher the kinetic energy
it has. If it is stationary it has no kinetic energy!
KE also depends on the mass of the object.
Where
- Ek = kinetic energy (in joule)
- m = mass (in kg)
- v = velocity in m/s
This equation shows us that the kinetic energy of an object
is directly proportional to its mass and to the square of its speed.
That means if you double the mass - you double the KE,
triple the mass - triple the KE etc. The KE depends on the mass.
It also means that for a doubling speed, the KE will increase
by a factor of four; for a triple increase in speed, the KE will increase
by a factor of nine; etc. The KE is dependent upon the square of the speed.
KE (like all forms of energy!) is a scalar quantity -
it has magnitude (size) but no direction.
Questions