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Homework Help: Does this answer make sense?

  1. Sep 19, 2010 #1
    1. The problem statement, all variables and given/known data
    Is this equation any good for finding a

    x=1/2 at2+v0t +x0
    Given that v0t=0 and x0=0

    I am trying to find the acceleration give that I dropped an eye dropper at 20cm and the average time was 0.116sec

    2. Relevant equations
    I have isolated it to a, where it is A= 2x over t2

    3. The attempt at a solution

    I have calculated it to be 2972cm/s2, then i divided it by 100 to get 29.72m/s2. Isnt the standard 9.8m/s2. I have also timed other objects and it seems they are all different.
  2. jcsd
  3. Sep 19, 2010 #2

    Chi Meson

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    Science Advisor
    Homework Helper

    Your math is OK, it's your time that was faulty.

    Are you sure the starting height was 20 cm? That's 8 inches right? Your time corresponds to something that was dropped from 6 cm or 3 inches.

    What did you use to time the event? If it involved any form of human starting or stopping of the timer, that throws a +/- of 0.2 seconds into anything.
  4. Sep 19, 2010 #3
    you won't be able to find acceleration from the given data (I think). The acceleration will be 9.8 m/s/s.
  5. Sep 19, 2010 #4
    1.72 is the av. velocity and initial velocity = 0 therefore final velocity = 3.45 m/s

    acc = (3.45- 0)/0.116

    but it is wrong, I guess
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