But, due to the acceleration of gravity, which accelerates objects at or near the surface of the Earth at a rate of, roughly, 32.2ft per second, per second (called the Acceleration of Gravity) at Earth’s surface – this is a continuously accelerating cannonball – it is constantly gaining speed at that rate with the passage of time. If we want to determine the distance traveled by an accelerating object – say, a cannonball, dropped from a leaning tower, by Yosemite Sam – has fallen, after a given period of time, given in seconds (easiest to do in whole seconds), and, given that, after one second, the object has fallen a distance of 16.1ft., we might think that, after two seconds, the cannonball will have fallen twice that distance – 32.2ft – since, twice the amount of time has elapsed since the start of the first second. Here we will be primarily concerned only with speed, and we’ll take it step by step – it’ll be fun, you’ll see! It is a vector quantity (it has two components: speed and direction). Velocity, is the rate at which an object changes its position in space. (And, this could, very well, be one of them!) Nevertheless – it will help to remember, that: This, actually intrinsically simple problem, has gotten the best of me more times than I care to admit. The idea here applies to objects that are in free-fall: a condition where, the only physical influence on a given body, is gravity (in vacuo*, e.g., the vacuum of space). This seems to be, mainly, because people confuse acceleration with speed, and speed with velocity, and because they’re not taking atmospheric drag, resistance, or buoyancy into account…oh, and one more thing they do what I do – they over-think it! The statement: “An object in free-fall accelerates at a velocity of 32ft/sec2” (thirty-two feet per second, squared – or, 32 ft per second, per second) – is one of the most confusing ideas in physics for the non-physicist lay-person, myself included. Thirty-Two Feet Per Second, Per Second 2017DaleBryTheScienceGuy
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