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Homework Help: Position of an object

  1. Sep 3, 2011 #1
    The position of an object is given by x=At+Bt^2, where x is in meters and t is in seconds.
    a)What are the units of A?
    (express answers in terms of m and s)
    b)What are the units of B?
    (express answers in terms of m and s)

    I know this may sound silly, but I really don't understand what the questions are asking.
    Please help, thank you.
     
  2. jcsd
  3. Sep 3, 2011 #2

    ehild

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    Homework Helper

    The dimension of x is length, its unit is meter. The dimension of both At and Bt^2 has to be length. You can multiply and divide dimensions, but you can add quantities of identical dimension only.
    So the dimension of At [At]=dimension of A [A] times dimension of time [T], and it has to be length [L]: [At]=[A][T]=[L]. What is the dimension of A then?
    If you measure length in meters and time in seconds, what is the unit of A?


    ehild
     
  4. Sep 3, 2011 #3
    Isn't it meters?
     
  5. Sep 3, 2011 #4

    ehild

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    No. When multiplied by second, it will be meters.

    ehild
     
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