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Free Fall and Acceleration of Gravity

Free Fall and Acceleration of Gravity. Rene Smith. Introduction to Free Fall. GRAVITY. “Free-falling objects do not encounter air resistance”. What causes an object to free fall? . “Skydiving is not free falling because a human experiences air resistance as they jump out of a plane”.

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Free Fall and Acceleration of Gravity

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  1. Free Fall and Acceleration of Gravity Rene Smith

  2. Introduction to Free Fall GRAVITY • “Free-falling objects do not encounter air resistance” • What causes an object to free fall? • “Skydiving is not free falling because a human experiences air resistance as they jump out of a plane” • The longer an object free falls, the faster it will fall

  3. But wouldn’t anything that is dropped experience air resistance? No. • To free fall an object must: -be heavy in weight -fall for a moderately short amount of time -move fairly slow

  4. “All free-falling objects (on Earth) accelerate downwards at a rate of 9.8 m/s^2” • However, to be in free fall does not necessarily mean that an object must be traveling in a downward direction.

  5. Free Fall In Action If you were to drop a softball and a piece of paper from the same height, at the same time, which object would experience free fall? The softball. The piece of paper experiences air resistance.

  6. The Acceleration of Gravity • Merriam-Webster Dictionary defines the acceleration of gravity as “the acceleration of a body in free fall under the influence of earth's gravity expressed as the rate of increase of velocity per unit of time” • This standard numerical value is so important to scientists that it was given its own special name—the symbol g.

  7. How is it calculated? • The standard value of g is 9.8 m/s/s, which is often rounded up to 10 m/s/s for rough calculations. • Air resistance: the force of air molecules striking a moving object • In the absence of air resistance, all objects will accelerate at the same rate • This constant velocity is called terminal velocity • At this point, the object is said to be in “free fall”

  8. MorewithCalculations • A= ∆v = -9.8m/s t 1 s • Positive (+) shows the UP direction • Negative (-) shows the DOWN direction • When calculating for free fall, always use the negative direction. • When solving problems in free fall, use any of the following formulas. -vf= vi + at -d = ½ (vf + vi)t -d = vit = ½ at2 -vf2 = vi2 + 2ad • Write the givens, figure out which variable you want to solve for, and determine which formula to use to find that answer.

  9. Just for Fun! • Due to variations in latitude, longitude, and geological structure of various regions of the world, there are some slight differences in the value of the acceleration of gravity here on Earth. These are based off gravitational fields.

  10. “Free Fallin” Graphs

  11. This position vs. time graph is representing the accelerated motion. • The reason the line is curved on this graph is because the object started out with a very small and slow velocity and started to take on acceleration g = (9.8 m/s/s)

  12. This graph is representing the velocity. On this Velocity vs. time graph the line is straight. Since a free-falling object is undergoing an acceleration (g = 9.8 m/s/s, downward), it would be expected that its velocity-time graph would be diagonal. A further look at the velocity-graph reveals that the object starts with zero velocity and finishes with a large, negative velocity.

  13. Terminal Velocity • Terminal Velocity is the term that many scientists use to show that an object has reached when the force of drag acting on it is equal to the force of gravity acting on the object in free fall.

  14. Sources • http://www.skydive-dc.com/ • http://www.physicsclassroom.com/class/1dkin/u1l5e.cfm • http://www.physicsclassroom.com/class/1dkin/U1L5a.cfm • http://www.batesville.k12.in.us/physics/phynet/mechanics/kinematics/FreeFallIntro.html • http://www.angelfire.com/psy/freefall/freefall.htm • http://www.hometeamsonline.com/teams/default.asp?u=WVHSSOFTBALL&sport=softball&t=c&p=home&s=softball • http://foundinapieceofpaper.blogspot.com/2010/10/today-my-mom-scolded-me-for-wanting-to.html

  15. Sources • http://www.merriam-webster.com/dictionary/acceleration%20of%20gravity • http://www.physicsclassroom.com/class/1dkin/u1l5b.cfm • http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=d34e8683df527e3555153d979bcda9cf&title=Gravitational%20Fields&theme=red&i0=Buchanan%2C%20VA&podSelect=&includepodid=Input&includepodid=GravitationalFieldStrength • Our textbook notes

  16. Sources • http://www.physicsclassroom.com/class/1dkin/U1L5c.cfm • http://hypertextbook.com/facts/JianHuang.shtml • http://www.wisegeek.com/what-is-terminal-velocity.htm • http://tap.iop.org/mechanics/drag/209/page_46353.html

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