How does Newton’s Third Law Apply when, say, pushing a ball through space?

Question

Wouldn’t an equal and opposite be exerted on your hand, thus canceling out the force and having no net change on the ball?

Noticeably different from a rocket, where propelled material is the force that drives the rocket forward.

I used to remember the answer to this question, but my physics is kinda fuzzy.

In: Physics

Answer 1

You can think of Newton’s Third Law as meaning something like “forces come in pairs”. There are a couple of easy rules to identify the forces in action/reaction pairs:

First, the forces in a pair always act on *different objects*. If one force is acting on the ball, then the reaction force cannot be another force acting on the ball.

Second, the forces in a pair are always *the same type of force*. If the force in question is a contact force (like a hand pushing on a ball), then the reaction force *also* must be a contact force. If the force is gravitational, then the reaction force must also be gravitational, etc.