Work and energy
The concept
of work is strictly defined in physics and is related to the resistance
to the force on the given path - work=force x passed path.
Energy
There
several kinds of energy and are divided into: kinetic energy (energy
of motion) and potential energy (energy stored in the environment).
The potential energy is divided into: elastic potential energy and
gravitational potential energy.
Kinetic
energy
When the
work is done force F can be changed; also the path x2-x2 can be
long and short; but in the final formula there is only mass and
final and starting speed of the body. When the body is moved along
the horizontal plane with no friction, that work of the force goes
only to raising the speed of the body, then that work is equal to
the change of the kinetic energy. If the mass m is move with the
speed v, her kinetic energy is 1/2mv2. It means that for the acceleration
of the mass m from the state of standstill to the speed v the following
energy has to be spent: 1/2mv2. On the other hand , if the body
is slowing down under the work of any force, it's kinetic energy
is falling.
Potential
energy
When stopping
the body looses kinetic energy, and it is in some way stored in
the environment. The energy stored like this is called potential
energy.
Power
In
many cases it is necessary to observe the speed at what the work
is done, or to say quantity of the work done in the specified period
of time. The speed by which the work is done will be called power.
The unit for the power is Watt P=w/t.