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Homework Help: Kinematics Problems

  1. Sep 16, 2013 #1
    I don't know what to do for these three questions and they're due on Wednesday

    1. The problem statement, all variables and given/known data
    a. A sprinter can accelerate with constant acceleration for 2.28s before reaching top speed.
    He can run 148.0m in 16.6s. What is his speed as he crosses the finish line?

    b. A car accelerates at 2.15m/s2 along a straight road.
    It passes two marks that are 29.5m apart at times t=3.95s and t=4.85s.
    What was the car's velocity at t=0?

    c. You've attached a rocket to the rear of a small car
    The rocket provides a constant acceleration for 4.68s.
    As the rocket shuts off, a parachute opens and slows the car at a rate of 3.43m/s2.
    The car passes the judges' box, 878.0m from the starting line, exactly 14.0s after you fire the What is the car's speed as it passes the judges?

    2. Relevant equations

    3. The attempt at a solution

    I don't even know where to start I'm just too stressed
  2. jcsd
  3. Sep 17, 2013 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    Chill and start by recalling what equations govern accelerated motion.

    It is also suggested that you post one problem at a time.
  4. Sep 17, 2013 #3


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    Science Advisor

    First, Don't panic! Second, somebody on here quoted a problem-solving methodology I didn't know - GRASP. It stands for

    Given - list the quantities that are in the question.
    Required - list the quantities that you are supposed to find.
    Asess - what equations do you know that link the things that you listed? Your textbook's index is helpful if nothing springs to mind.
    Solve - do the maths.
    Paraphrase - write out the answer.

    See if you can do the first three at least.
  5. Sep 17, 2013 #4
    I've tried to solve it already but I'm just not getting the right answers, I just need to see how someone else goes about solving it before I try it again
  6. Sep 17, 2013 #5


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    Staff Emeritus
    Science Advisor
    Homework Helper

    If you want help, post your work so far. We won't do your HW for you. You don't have much time left.
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