Mechanical energy conversion is when mechanical force turns into heat. For example, rubbing hands turns into heat and warm up hands. Conversion of energy is when potential energy is converted into kinetic energy , For example water in a tank when flowing through a pipe changes potential to moving energy.
Friction is the loss of energy when a body moves on a plane. Conservation of energy refers to a process in which energy to the process is equal to energy put of the process.
Energy resources are ones which can supply energy. For example, sunlight and wind. Fossil fuels are fuels found below ground. For example, oil and natural gas.