Mechanical energy

Mechanical energy
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Mechanical energy is ability to do work.

The energy acquired by the objects upon which work is done is known as mechanical energy. In physics, mechanical energy describes the sum of potential energy and kinetic energy present in the components of a mechanical system. Mechanical energy is the energy associated with the motion or position of an object.

Any object that possesses mechanical energy – whether it is in the form of potential energy or kinetic energy – is able to do work. That is, its mechanical energy enables that object to apply a force to another object in order to cause it to be displaced.

The mechanical energy of an object is the sum of its energy in motion and its stored motion. This means it is the sum of its kinetic and potential energy. Although the kinetic and potential energy of an object can change, its mechanical energy remains constant. This is because kinetic and potential energy change proportionately.


How to calculate mechanical energy

The total amount of mechanical energy is the sum of the potential energy and the kinetic energy. This sum is simply referred to as the total mechanical energy (TME):


As we know there are 2 type of potential energy – gravitational potential energy and elastic potential energy. Given this fact, the above equation can be rewritten:

TME = PEgrav + PEspring + KE




1) A drawn bow possesses mechanical energy due to its stretched position (elastic potential energy).

bow arow

2) The weight lifter applies a force to cause a barbell to be displaced. The barbell then possess mechanical energy – all in the form of potential energy.

weight lifter

3) Satelite is an example of a mechanical system. A satellite that is orbiting the Planet only influenced by the conservative gravitational force and the mechanical energy is therefore conserved.


4) Hammer utilizes mechanical energy to do work. The mechanical energy of a hammer gives the hammer its ability to apply a force to a nail in order to cause it to be displaced. Because the hammer has mechanical energy (in the form of kinetic energy), it is able to do work on the iron.


Mechanical energy facts

  • Every object in motion contains mechanical energy.
  • Mechanical energy cannot be created nor destroyed, it can be converted to another type of energy.
  • The mechanical energy of an object is associated with the objects’ position and motion.
  • When an object loses mechanical energy, it gains heat or increases in temperature.
  • If an object contains mechanical energy, then it has the ability to do work.
  • A wreaking ball, sound, and a bird all contain mechanical energy.