Why do scientists track the energy in a system?

The supply of energy and of each needed chemical element restricts a system operation -- for example , without inputs of energy ( sunlight ) and matter ( carbon dioxide and water ) , a plant cannot grow. Hence , it is very informative to track the transfers of matter and energy within , into , or out of any system under study.

Hope it helps

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.