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Free fall

Free fall. Antonian Physics Mrs. Woods – 2014-2015. Does an apple accelerate while falling? Gravity causes the apple to accelerate downward once it begins falling. Air resistance affects the acceleration of a falling object. How fast.

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Free fall

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  1. Free fall Antonian Physics Mrs. Woods – 2014-2015

  2. Does an apple accelerate while falling? • Gravity causes the apple to accelerate downward once it begins falling. • Air resistance affects the acceleration of a falling object. How fast

  3. Let’s imagine there is no air resistance and that gravity is the only thing affecting a falling object. • Such an object would then be in free fall. • Freely falling objects are affected only by gravity. Free fall

  4. http://youtu.be/E43-CfukEgs

  5. http://nypost.com/2014/11/03/worker-dies-after-being-hit-by-falling-tape-measure/http://nypost.com/2014/11/03/worker-dies-after-being-hit-by-falling-tape-measure/ Gravity kills

  6. Instantaneous speed = Acceleration x elapsed time V = gt What would the speedometer reading on a falling rock be 4.5 seconds after it drops from rest? How about 8 seconds after it is dropped? 15 seconds?

  7. Objects thrown upward At the highest point, when the object is changing its direction of motion from up to down, its instantaneous speed is zero. The object is accelerating because its velocity is changing.

  8. Instantaneous speed is the same whether the object is moving up or down. The velocities are different because they are in opposite directions. • During each second, the speed or the velocity changes by 10 m/s. The acceleration is 10 m/s2 the entire time.

  9. D = ½ gt2 • An apple drops from a tree and hits the ground in one second. What is its speed upon striking the ground? • V = gt = (10 m/s2) (1 s) = 10 m/s • What is its average speed during the one second? • Vavg = vi + vf /2 = 5 m/s • How high above the ground was the apple when it first dropped? • D = ½ gt2 = (5 m/s2) (1 s)2 = 5 m Free fall: how far

  10. An apple drops from a tree and hits the ground in 1.5 s. What is its speed just before it hits the ground? • A skydiver jumps from a helicopter hovering at high altitude. If there were no air resistance, how fast would she be falling 12 s after jumping? • An apple drops from a tree and hits the ground in 1.4 s. How far does it fall? • What vertical distance will a body dropped from rest fall in 12 s of free fall? • Kenny Klutz drops his physics book off his aunt’s high-rise balcony. It hits the ground below 15 s later. (a) With what speed does it hit? (b) How high is the balcony. Ignore air drag. Exit ticket – answer on index card provided and leave in red bin as you exit

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