Can you explain the concept of energy conservation?

Explain the following extract from the Feynman lectures so that a 10th grader can understand.Note that I do not want you to explain what conservation of energy is,I just want understand the following extract clearly.Try to be as simple as possible. ...

The escape speed of an object is the term used for the initial speed needed to escape from the surface of a planet or moon so that, after escape, the object has zero speed left. Apply the concept of conservation of mechanical energy (=GPE+KE) in order...

The law of conservation of energy is energy can be neither created nor destroyed by ordinary means. Thats what my book gave me as a definition.

Do physicists take "The Law of Conservation of energy" as an axiom because it agrees with the experiments or has any modern theoretical model like general relativity, quantum mechanics been able to prove it theoretically.

If energy cannot be created or destroyed, and E=mc^2 then surely you can destroy energy by turning it into matter and vice versa? Where an I going wrong with this? Thanks

when wood is burned,energy is released in the forms of heat and light. but remember to use the terms combustion, exothermic, and chemical energy

would enact and what energy source you would explore for future use???

The Hypothesis is thus. Based on the scientific law of Conservation of energy, and the fact that Atoms are in essence types of solidified concentrated energy. I am led to believe that Energy in all it's forms is the Original uncreated universal constant...

I need a little help answering this seemingly simple question: can energy exist without mass? At first I thought this an easy answer. Simply, no. Einsteins famous equation E=mc^2 shows us that energy and mass are directly proportional, so without mass...