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Paul Hewitt on Free Fall and Basic Kinematics

Added Nov 04, 2019 •

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Kinematic equations and free falling objects with Professor Paul Hewitt

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let's discuss freefall when air resistance doesn't affect the motion of a falling object when the only force acting on the object is that due to gravity we say the object is in free fall here we have a boulder heavy enough that air resistance is negligible for shortfalls Phil visger drops the boulder what's the edge of a tall cliff since only gravity is significant the boulder experiences free fall will only discuss freefall here the falling Boulder picks up speed as it falls this pickup is acceleration acceleration equals the time rate of change of velocity given by the equation is Delta V / delta T straight-line motion we can use the terms velocity or speed interchangeably recalled its speed is the magnitude of velocity in free fall during each second of all the exact same pickup of speed occurs we say the boulder Falls with constant acceleration you're still at the top of a cliff ready to drop the boulder over the edge he drops it and it accelerates downward what's the price of a speedometer we're attached to Phil's Boulder so that we could watch the game and speed is the boulder Falls we wouldn't be able to see the readings so we blow up the speedometer for better viewing we start from rest so the speedometer reading begins at 0 this is our initial speed a speedometer also has an odometer that measures distance traveled misreading is set to 0 at the time equals 0 mark Phil releases the bowler with a speedometer and one second later the boulder is gained 10 meters per second during this week second interval the odometer reading is 5 meters that's 5 meters not 10 as well explain later for now just concentrate on changes and speed one second later older again gains 10 meters per second and the speedometer reading is 20 meters per second odometer reading is 20 m one second later the boulder again gains 10 meters per second and the speedometer reading is 30 meters per second and our odometer reading is 45 m and another second later another gain of 10 meters per second finds the speedometer reading meters per second at the four-second Mark we find our Boulder his Fallen ATM at the instant its speed is as set 40 meters per second let's make sense of ratings first the acceleration we see that acceleration equals Delta V / delta T equals 10 meters per second for one second equals 10 / 1 second X second which equals 10 meters per second squared notice how the symbol for second appears twice first the time velocity and second the time during which velocity changes that's why the second squared how do we know that the acceleration of Free Fall is 10 meters per second Square because with measure time and time again you can do the same with actual measurements in the lab where you'll get 9.8 meters per second Square to simplify calculations we round this off to 10 meters per second squared we called the acceleration of Free Fall G that's G for gravity from g equals Delta V / delta T we can say that Delta V equals delta T or simply equals Gigi which reads the speed gained in an interval of time T is equal to the acceleration times that time t since g equals 10 meters per second squared we can write speed gained as V equals 10 meters per second squared times t notice how this equation accounts for the white speed ratings had one second V equals 10 meters per second squared * 1 seconds equals 10 meters per second at 2 seconds V equals 10 where's the second squared times 2 seconds equals 20 meters per second at 3 seconds V equals 10 meters per second squared times 3 seconds equals 30 meters per second at 4 seconds equals 10 meters per second squared times 4 seconds equals 40 meters per second how about distance Fallen here's word equations they're thinking from the equation for average speed we know the distance traveled equals average speed multiplied by time that is D equals average speed times time where average speed is V Sub Zero initial speed V the final speed / 2 * t and we see her initial speed in this case is zero Lisa Beth is the final speed at time t and we have distance equals 1/2 g t x t and t x t is t squared show the dish Fallen is 1/2 g t Square instead of D we substitute why the common symbol for vertical distances 4 numerical values distance of fall is given by I'm half of 10 m per second squared which is 5 meters per second squared x t squared disagrees with the 520 meters 45 M and 80 M odometer distance Starfall got it not really until you have given some set the time to this in this lesson was considered the simplest case of free fall starting from a rest position did Phil fish occur throws the boulder downward rather than dropping it supposed parts and initial speed V Sub Zero the speed when a stopwatch begins at zero-hour equations can take this instead of equals GT we say V equals V sub zero plus GT that is the speed at any point will be the initial speed plus that game by acceleration and instead of distance y equals 1/2 g t Square we add y equals a National Speed X time so the following distance will be that due to an initial speed plus the distance it would fall due to acceleration getting back to falling from rest initial velocity 0 I leave you with three questions question 1 at 5 Seconds what will be the speed of the boulder how far from the top will it have fallen in 5 seconds + 3 what will be its acceleration at this V II think about that until next time good energy

Uploaded by Shawn Mize.

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Paul Hewitt on Free Fall and Basic Kinematics

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