https://teddyrookbook.com/physics/rocket-boys/Recent content in Rocket Boys Math and Physics on Teddy Rook Bookhttps://teddyrookbook.com/img/share.jpghttps://teddyrookbook.com/img/share.jpgHugoenhttps://teddyrookbook.com/physics/rocket-boys/units-sig-figs/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/units-sig-figs/Change feet to meters and miles to feet with conversion factors, and keep only as many digits as the measurement deserves. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/flight-graphs/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/flight-graphs/Read a rocket's velocity-time graph: the slope is acceleration, the area is height, and the top of the flight is where the line crosses zero. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/launch-statistics/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/launch-statistics/Fly the same rocket again and again: the mean says what to expect, and the range and standard deviation say how much to trust it. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/newtons-laws-thrust/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/newtons-laws-thrust/A rocket pushes its exhaust down and the exhaust pushes the rocket up. Net force, not thrust alone, sets the acceleration. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/thrust-to-weight/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/thrust-to-weight/A rocket leaves the pad only if its thrust beats its weight. The ratio of the two tells how hard it jumps and how fast it leaves the launch rod. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/impulse-momentum/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/impulse-momentum/Total impulse is the area under the thrust curve. It equals the change in momentum, and it is what a motor's letter class measures. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/rocket-equation/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/rocket-equation/As a rocket throws mass backward it gets lighter. Adding up those small pushes with calculus gives Tsiolkovsky's equation, $\Delta v = v_e \ln(m_0/m_f)$. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/nozzles-concept/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/nozzles-concept/Why a rocket nozzle narrows and then widens: pressure turns into exhaust speed, and faster exhaust means more thrust from the same mass flow. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/calculus-of-motion/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/calculus-of-motion/Velocity is the derivative of height, and the change in velocity is the area under the acceleration graph. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/powered-flight/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/powered-flight/While the motor burns, the net force gives a steady acceleration (in a simple model). Burnout speed and height follow from the kinematic equations. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/coasting-apogee/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/coasting-apogee/After burnout the rocket is still going up, slowing by 9.8 m/s every second until it stops at apogee. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/energy-burnout-apogee/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/energy-burnout-apogee/Kinetic energy at burnout turns into potential energy on the way up. Comparing the two shows how much energy drag took. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/drag/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/drag/Air pushes back harder the faster you go, about as the square of speed. With drag there is no neat formula, so we step through the flight a little at a time. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/stability/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/stability/A rocket flies straight when its center of mass is ahead of its center of pressure, so a gust turns it back into the wind like a weather vane. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/range-angle/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/range-angle/Tilt the flight and some of the speed carries the rocket sideways. Range depends on the angle, with the longest at 45 degrees in the ideal case. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/altitude-tangent/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/altitude-tangent/Stand a measured distance from the pad, sight the rocket at its highest point, and the tangent of the angle times the baseline gives its height. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/angle-error/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/angle-error/A one-degree slip in the angle changes the height by an amount that grows fast at steep angles. Choosing the baseline well keeps the error small. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/triangulation/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/triangulation/Two people sighting the same rocket from two places can find its height without measuring the distance to the rocket at all. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/gravity-orbits/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/gravity-orbits/An orbiting satellite is falling all the time, but it moves sideways so fast that the ground curves away beneath it. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/escape-velocity/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/escape-velocity/Fast enough and an object never comes back: kinetic energy beats the whole gravitational well. Escape speed is $\sqrt{2}$ times circular orbit speed. Rocket Boys Math and Physics · Physics Ladderhttps://teddyrookbook.com/physics/rocket-boys/kepler-ellipses/Mon, 01 Jan 0001 00:00:00 +0000https://teddyrookbook.com/physics/rocket-boys/kepler-ellipses/Real orbits are ellipses with Earth at one focus. The satellite speeds up near the low point, and the size of the ellipse sets the period. Rocket Boys Math and Physics · Physics Ladder