Physics, From the Ground Up, Ep. 14: P2 · Forces and Newton's Laws (Part 1: Newton's Three Laws)

Description: What keeps a moving thing moving? It took about two thousand years to get the answer right. Part 1 of P2 follows the idea from Aristotle through Galileo and Descartes to Newton's three laws, then puts F = ma to work: weighing astronauts in orbit, the Saturn V lifting off, free-body diagrams, and how you can walk at all. Chapters: 0:00 Why do things move? 1:31 Motion needs a push? 2:47 Galileo's ramps 4:02 Straight lines 5:25 Newton's first law 6:48 What is a force? 8:24 F = ma 10:04 Using F = ma 11:48 Mass and weight 13:48 Weighing in space 15:14 Lifting off 16:57 Free-body diagrams 19:18 Action and reaction 20:45 Why don't they cancel? 22:39 Walking and rockets 24:37 Common mistakes 26:02 Recap and what's next WHAT YOU'LL LEARN • Inertia and Newton's first law: forces change motion, they don't keep it going • Net force and F = ma, with every step worked through • Mass and weight (W = mg), and why heavy things don't fall faster • Free-body diagrams: a five-step routine • Newton's third law: why action and reaction never cancel, and how walking and rockets work COMPANION WEBSITE Notes, key equations, sources, practice problems with full solutions, and further learning: https://relativelypuzzled.com/ground-... SOURCES • Aristotle, Physics, Books VII and VIII (4th century BC). • Galileo, Dialogue (1632), Second Day, and Two New Sciences (1638), Third Day: the two ramps. • René Descartes, Principia philosophiae (Amsterdam, 1644), Part II. • Isaac Newton, Philosophiae Naturalis Principia Mathematica (London, 1687): the laws of motion; Halley paid for the printing. • NASA: the Space Linear Acceleration Mass Measurement Device (SLAMMD) on the ISS. • Saturn V for Apollo 11 (16 July 1969): about 33 MN of thrust, about 2.9 million kg at liftoff (NASA figures). #physics #newton #forces