Notices
Results 1 to 8 of 8

Thread: Acceleration

  1. #1 Acceleration 
    Forum Masters Degree thyristor's Avatar
    Join Date
    Feb 2008
    Location
    Sweden
    Posts
    542
    Hi!
    Suppose we have a body that undergoes free fall. We drop it from a height h, which point we henceforth will call s0. The acceleration=a and it is constant. We sample the body's position in timeintervals which are equal. An interval has the length t1.
    Then I get that during the first time intyerval, the body would travel the distance
    s1=(a*(t1)^2)/2
    and during the second it would travel the distance
    s2=(a*(2*t1)^2)/2-s1=(a*4(t1)^2)/2-(a*(t1)^2)/2=(a*3(t1)^2)/2=3*s1
    However, according to an experiment we did at school, this is wrong.
    Have you got any idea?


    373 13231-mbm-13231 373
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Freshman
    Join Date
    Jan 2009
    Posts
    35
    Can't help with homework.
    Advice: go back and look at the equations and check for assumptions.


    I had a simple dream: a dream to kill all humans, and this is how you repay me?
    Reply With Quote  
     

  4. #3  
    Forum Masters Degree organic god's Avatar
    Join Date
    Feb 2008
    Location
    London
    Posts
    567
    the algebra is correct therefore we can place the blame on 2 main factors.

    1) assumptions in the algebra

    2) experimental error

    The only assumption that is strictly not true is constant acceleration as the body will experience drag.

    experimental errors can come down to the uncertainty of the equipment and how you measured your variables.

    incidentally what kind of range of heights are you measuring over?
    everything is mathematical.
    Reply With Quote  
     

  5. #4  
    Forum Masters Degree thyristor's Avatar
    Join Date
    Feb 2008
    Location
    Sweden
    Posts
    542
    Quote Originally Posted by organic god
    the algebra is correct therefore we can place the blame on 2 main factors.

    1) assumptions in the algebra

    2) experimental error

    The only assumption that is strictly not true is constant acceleration as the body will experience drag.

    experimental errors can come down to the uncertainty of the equipment and how you measured your variables.

    incidentally what kind of range of heights are you measuring over?
    1,33 meters
    373 13231-mbm-13231 373
    Reply With Quote  
     

  6. #5  
    Forum Masters Degree thyristor's Avatar
    Join Date
    Feb 2008
    Location
    Sweden
    Posts
    542
    Quote Originally Posted by JekPorkins
    Can't help with homework.
    Advice: go back and look at the equations and check for assumptions.
    I wouldn't say it's exactly homework, it's rather a question that came to me which is related to the experiment.
    373 13231-mbm-13231 373
    Reply With Quote  
     

  7. #6  
    Forum Isotope
    Join Date
    Feb 2009
    Location
    Transient
    Posts
    2,914
    air resistance and the human element can attribute to the errors.
    Reply With Quote  
     

  8. #7  
    Moderator Moderator Dishmaster's Avatar
    Join Date
    Apr 2008
    Location
    Heidelberg, Germany
    Posts
    1,624
    You have to estimate the measuring errors on distance and time and do algebraic error propagation in order to evaluate, whether the experimental setup was able to verify theory. I suspect, the overall uncertainty was huge.
    Reply With Quote  
     

  9. #8  
    Administrator KALSTER's Avatar
    Join Date
    Sep 2007
    Location
    South Africa
    Posts
    8,231
    However, according to an experiment we did at school, this is wrong.
    Have you got any idea?
    Can you explain how the experiment was conducted? Was it in a vacuum tube? What object did you use to test it? How did you measure it?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •