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Physics Kinematics correction

  1. May 31, 2014 #1
    Hi, I have some questions regarding Kinematics:

    1. If an object is accelerating at 9.8 m/s^2, how much time does it Need to reach ten percent of the Speed of light?

    Speed of light: 299 792 458 m / s -> 10% -> 299 792 45,8 m / s

    t = v/a -> 299 792 45,8 m / s / 9.8 m/s^2 = 3 059 106.714 s = 849.8 h


    2. An object is uniformly accelerated at a = 4m/s^2. At time t, the object has a velocity v = 50 m/s. What is its velocity before and afterwards?

    t = v/a = 50m/s / 4m/s^2 = 12.5 s

    7.5s * 4m/s^2 = 30 m/s
    17.5 s * 4m/s^2 = 70 m/s

    3. The fastest dragster reaches 632 km/h in 3.72s. Find its average acceleration.

    a=v/t -> 175.6m/s / 3.72s = 47.2m/s^2


    Are all my Solutions true?
     
  2. jcsd
  3. May 31, 2014 #2

    adjacent

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    Gold Member

    Correct
    This question does not make much sense to me. What do you mean by before? How many seconds before? Howmany seconds afterwards?
    Correct
     
  4. May 31, 2014 #3
    This question does not make much sense to me. What do you mean by before? How many seconds before? Howmany seconds afterwards?

    Sorry, it's 5s.
    Thank you for the correction!
     
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