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Is this equation for acceleration on this website wrong?

  1. Jun 11, 2010 #1
    Greetings, i've been learning the mathematics of classical physics from a website called "A physiscs teacher" (http://aphysicsteacher.blogspot.com/search/label/acceleration). While looking through the equations on the acceleration i think i found a mistake made by the website.

    A bus starts from rest and accelerates at a rate of 2.5 m/s2 for a time of 50 s. Determine the distance travelled by the bus during the acceleration phase.

    Now let us identify the different variables involved.

    u the initial speed = 0 m/s

    t time taken = 50 s

    a acceleration = 2.5 m/s2

    s distance travelled = ???

    If we want calculate s the distance travelled we will have to use the second equation of motion

    S = ut + 1/2at2

    Substituting the different values we get

    S = ut + 1/2at(squared)

    = o*50 + 0.5 *50(squared)

    = 0 + 0.5*2500

    =1250 m

    My problem with this question comes in when after the values have been substituated.
    = o*50 + 0.5 *50(squared), im kinda new to the mathematical side of physics but shouldn't the acceleration (2.5) have been substituated in as well to make it
    = o*50 + 0.5 *2.5 *50(squared) get an answer of 3125?
     
  2. jcsd
  3. Jun 11, 2010 #2
    If
    a=2.5 m/s²
    t=50s
    u=0
    then
    s = ut + ½at²
    s = 0 + ½ x 2.5 x 50²
    s = 3125m
     
  4. Jun 11, 2010 #3

    Doc Al

    User Avatar

    Staff: Mentor

    OK.

    Oops!


    Of course. The webpage goofed in leaving out the acceleration. (It was obviously an oversight.) Send the author an email suggesting that he correct the page! He will appreciate the correction.

    Good catch. :wink:
     
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