Potential energy

The potential energy of an object is the energy stored in an object or system. Denoted as E_{p}.

Generally speaking, potential energy refers to potential energy caused by gravity and is proportional to the mass and height of an object.

When a spring is deformed by external force, it has energy also, which is called ‘potential energy by elastic force’.

\[ \begin{align} Potential\;energy\;caused\;by\;gravity\;E_p &= 9.8 m h \\ Potential\;energy\;by\;elastic\;force\;E_p &= \frac{1}{2}mx^2 \end{align} \]

m: mass(kg)

h: Height(m)

k: spring constant(N/m)

x: deformation length of spring(m)

Kinetic energy

Kinetic energy is the energy in a moving object or particle. Denoted as E_{k}.

Since the kinetic energy at rest is ‘0’, the kinetic energy becomes the energy required to accelerate an object of mass m to speed v.

\[ Kinetic\;energy\;E_k = \frac{1}{2}mv^2 \]

m: maxx(kg)

v: velocity(m/s)

Energy conversion

One energy can be converted to another. If there are no losses due to friction, the energy can be converted to 100% other energy.

The lost energy escapes with the form of heat.