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How much time does an object use to travel.

  1. Nov 2, 2014 #1
    1. The problem statement, all variables and given/known data
    How much time does the object use to travel 12m down a plane. The object has a constant acceleration of 1m/s2 and the starting velocity is 5m/s.

    2. Relevant equations
    S=V(starting velocity)*t+1/2*a*t2

    3. The attempt at a solution
    Here I struggle with changing the formula. I could just leave both t's on the left side and then use square root. But I have a slight feeling that this is not right.
     
  2. jcsd
  3. Nov 2, 2014 #2

    Simon Bridge

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    Very close - for that to work, the LHS needs to be a complete square.

    Hint: quadratic equation

    Aside:
    I'm intrigued by the wording. Is time the sort of thing that gets used up by objects ... you know, like a car uses petrol?
    Probably the question wants to know how much time is taken or occupied by an activity.
     
  4. Nov 2, 2014 #3
    Yea, it's quite hard to word yourself correctly in another language. Especially in math. But I will check out quadratic equation! Thank you!
     
  5. Nov 2, 2014 #4

    Simon Bridge

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    Oh it was a translation?! Well done - I couldn't tell. I wondered if maybe you just had a new-age physics teacher ;)
    Since English is a second language ... I'll say a bit more.
    The equation you are trying to solve can be put in form: ##At^2+Bt+C=0## - do so: A, B, and C, may be made of several variables.
    You should recognize that as the equation for the roots of a parabola... you should know an equation to solve that. $$t\in \frac{-B\pm\sqrt{B^2-4AC}}{2A}$$
     
  6. Nov 3, 2014 #5
    I think I need some more help on that one. First of all how do I achieve 0 on the right side of the equation. Second how do I determine the variables?

    And thank you for all your help! It seems like I lack some fundamentals in physics, heh...
     
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