Today I had scheduled myself for a study session in the AM. I slept in a bit (I must say this no-alarm-clock business is divine), went for a walk, brewed up a mug of decaf coffee in my French press, and go to work. I only had two chapters today: Newton’s Laws and Applications of Newton’s Laws. Which means–heck yeah, free body diagrams!
Free body diagrams are probably loathed by most introductory physics students. In fact, I don’t recall being fond of them myself, way back when in my AP Physics course in high school. But seriously, they are SUPER cool. I love the way they simplify down problems that sound crazy complicated into something solvable. Plus they are the quintessential “spherical cow” object! Throw in a couple massless, frictionless pulleys and you’ve got yourself a party.
I have to admit that I had to read the sections on rolling friction a couple times. I know this is basic stuff, but for some reason my brain does a little fritz when I first try to picture the forces involved and I really have to break it down for myself.
Today’s fun “new” fact: The angle of repose! This is the maximum angle that something will stay stationary due to the force of static friction. I always like nifty little things like this that are way simpler than you might think at first glance. Also it’s kind of funny that this is something I forgot given that this equation was one I learned for the pGRE like six months ago.