text: Cool, you have asked what is totally QUESTION NUMBER ONE in basic physics. It's an exciting question which many teachers secretly don't understand and so their students get this hazy idea and kind of go thru the motions. Here's a way to remember and understand through a kooky made-up story.\n\nWow, it is so basic, that it took a super-genius, I mean way smarter than Einstein, to figure it out. A good old farm boy, astrologer, magician & alchemist, religious fanatic, mathematician and all around kook. Yep. Sir Isaac Newton. You gotta wonder what kind of parents would name their kid "Sir"\n\nWell we all know what a force is, it is a sort of push or pull -- think of it as something that changes or *tries to change* the motion of stuff.\n\nNewton first figured out that if you leave a thing alone, or if the pushes and pulls on it cancel out, then it will sit there like a lump. Like those drivers wearing hats, and like sit there after the light has already turned green two minutes ago.\n\nOr else a thing will keep moving in the same straight line direction and speed like those drivers wearing hats who go 40 mph on the expressway with their turn signal blinking on and on. This is known as "THE HAT LAW".\n\nAll was well until he noticed that things move faster in an amount equal to how much you bully them or push them around. Twice the force, twice the fasterness and fasterness (also known as acceleration). This is called the "YOU BIG BULLY LAW".\n\nThen he discovered a fly in the ointment. His HAT and BULLY laws didn't really explain all that much. Something was gumming up this beautiful theory. We call it MASS and it is still an unknown mystery as to what it really is. So we vaguely call it the amount of stuff or matter in a thing.\n\nSo he found out that for a certain force the faster-isity (acceleration) is cut in half if you double the mass. The bully has to push twice as hard to fasterize two little kids. So he was like "I'll just add that in, and all will be cool". The "YOU BIG BULLY LAW" and "THE HAT LAW" totally did it all. Wa ta da babee!\n\nBut then Newton had a road accident. He was gunning his Harley over London bridge at like 250 when a bug hit him in the mouth and knocked out one of his wooden teeth. He was all "Why am I so in pain?". And the bug as it squooshed said "Help! I'm a bug!"\n\nSo spitting out the splinters of his wooden tooth and the splattered bug, he had this revelation. He realized that because he was moving so fast, and the bug slowed down so fast, that even a eentsy mass like a bug was like taking a hammer to his tooth.\n\nHe noticed that the force was equal to the mass of the bug times the speed of impact all happening in a brief moment. Since Newton spoke Latin (he was the love child of Joe Newton and an Italian governess) he wrote "Fastus buggus ina momentum hurtus like crazy." Today we call this "momentum". It is just "mass times speed" or "force times a small moment of time".\n\nAnd he realized that the bug smashed up his tooth, but also that the bug was squashed (like a bug) because they were trading the EXACT same amount of momentum. The force on the tooth by the bug in the moment of time was PRECISELY equal to the smacko-ing the tooth used to stop the bug dead.\n\nHe said "Hey, like he broke my tooth, but I killed him soooo dead!" He did the math and found that the force of the bug on the tooth was equal to the force of the tooth on the bug!\n\nNo way did the two equal forces cancel, after all, his tooth was hammered to splinters, and the bug was flattened. They were equal and opposite, but since one was on the tooth, and the other force was on the bug they did serious damage! Today we call this the "HELP I'M A BUG" law.\n\nNow our man 'Zack was all set. He wrote down his three laws:\n\nTHE HAT LAW (beeep! beeep! Move it Hat G