Today I was sitting in a chair (with wheels on bottom) and decided to apply a force to a large desk. While I applied this force with my hand, my seat and I rolled backwards. My question is why is this so? I was thinking that if my hand is object "a" then it exerts a force on the desk (object "b"), F(ab) while the desk exerts a force F(ba) on my hand. Now if these action-reaction forces are equal and opposite then why do I accelerate backwards (or away from my desk)? What I think happens is that I DO accelerate the table but why can't I see its acceleration?
Newton's third law and ΣF=ma where F and a are vectors