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Newton's First Law is so counterintuitive that it is easy for students to believe that physics professors spend too much time in an abstract world that is fundamentally different from the real world. As poetically stated by one middle school student trying to get her mind around this dichotomy,
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| Objects in motion remain in motion in the classroom and come to rest on the playground. |
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| {center}{_}Objects in motion remain in motion in the classroom and come to rest on the playground.{_}{center} |
Importantly, over 300 years of scientific discovery confirms that you must modify your intuition to adopt Newton's first law as your phenomenological primitive. When you see a sliding book come to rest, you must realize that this is unnatural and requires the action of a force such as friction. When you push the book and it responds by traveling at constant speed (rather than accelerating), you must realize that constant speed implies no net force and search for another force acting opposite to your push (friction again).