The subject of a source can best be described as the main topic or area of concern. most important idea in the text. tendency to view something in a certain way. way the source wants people to feel or think.

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j ?

15. give an example for some particles or waves that are moving faster than light in everyday life 16. what is a laser? 17. what is an oscilloscope? 18. what does it means practically that nothing is faster than light in vacuum? 19. what is vacuum?

Does heating a metal wire increase or decrease its electrical resistance? why?