
Mark H. answered 04/13/19
Tutoring in Math and Science at all levels
If you apply 2 equal and opposite forces to an object, the "net force" is zero, and nothing happens. This is not what happens in response to Newton's 3rd law.
When you apply a force (to anything), you will sense the opposing force dictated by the 3rd law. If you didn't, the object would be instantly** displaced. The "reaction force" that you feel is due to the inertia of the object---i.e. the fact that it cannot start moving without a force. Imagine pushing on something that is 100X more massive than you are. You will feel the reaction force for a very long time, because the object accelerates VERY slowly. By contrast, if you push on a spec of dust or a ping-pong ball, you might feel nothing. With a very light object, the same reaction force is there, but only for the very short time it takes to accelerate.
**"Instantly" means that something travels between 2 points in zero time. This requires infinitely high acceleration, and therefor infinite force. for a very light object, the reaction force is there---it just does not last long enough for you to feel it.