16. Mechanical energy is the energy of either an object in motion or the energy that is
stored in objects by their position. Mechanical energy is also a driver of renewable
energy. Many forms of renewable energy rely on mechanical energy to adequately
produce power or convert energy.
Some everyday examples of mechanical energy are turning a doorknob, breathing in
and out, hammering a nail, riding a bicycle, sharpening a pencil, using kitchen
appliance, listening to music. The mechanical energy can be converted into two:
kinetic energy and potential energy. The expression for kinetic energy is 1/2
mv2 and for potential energy is mgh.
a) An object of mass 40 kg is raised to a height of 5 m above the ground. What is its
potential energy? If the object is allowed to fall, find its kinetic energy when it is
half-way down.
b) State law of conservation energy.
c) A freely falling object eventually stops on reaching the ground. What happens to
its kinetic energy? Write the conversion of energy taking place here.
