Quick engineering question…

Action-Reaction principle is only valid on mechanical system.
True or False?
Answer #1
false
Answer #2
Could you please explain a little?
Answer #3
KILLAH replied: Could you please explain a little?
Consult wikipedia!
http://en.wikipedia.org/wiki/Reaction_%28physics%29
Answer #4
I already tried wikipedia… I just can’t find an another example where it is valid…