Today we're going to discuss... however briefly... Newton's Third Law, which states:
Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction. This law is sometimes referred to as the action-reaction law, with F called the "action" and −F the "reaction". The action and the reaction are simultaneous.
That's from The Wiki. Here's an illustration of those forces of action and reaction in the real world, presented in the spirit of "a picture is worth a thousand words:"
We only include this specific example to encourage you to consider the laws of motion and their effects and because today is a BIG beach sorta day, bein' as how it's the height of summer. So go on... get out there! You might could see sumthin' similar to the above, assuming you live near a beach. I don't and more's the pity, because I LOVE to observe science in action.