1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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

    User Avatar
    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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook