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What does “Equal and Opposite” really mean?
Clearing up Newton’s Third Law (without math!)
My Degree is Good for Trivia
These days I work in software, but my physics knowledge can help if there’s a trivia question about science, or (as the article points out), explaining some things you might have heard but don’t make all that much sense to you.
Hopefully this helps if you’re learning physics or if you hear some physics concepts and think “that can’t be right…”
What I’ll seek to clarify is the misconceptions around equal and opposite reactions (Newton’s third law).
A Reaction, Well, what’s the Action?
Before we get to reactions, it’s good to start with actions. Things that cause you to speed up or slow down are the “actions” in this parlance, or “forces” to use the right physics terms.
If you’re not moving or moving at a constant speed, there’s no “net force” on you. You just stay still or in motion. (Newton’s 1st Law)
If all of a sudden you start speeding up (“hit the gas!”) then you’re experiencing a net force. (Newton’s Second Law). As a person, you can feel the chair press into you of a vehicle as you speed up or fly down a hill on your bike.
