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Homework Help: Physics Test Tomorrow

  1. Sep 20, 2015 #1
    1. Object 1 starts at 25 m and moves with a velocity of –5.5 m/s . Object 2 starts at 13 m and moves directly toward object 1. The two objects collide 0.65 s after starting. I need to find when they both collide and the velocity of Object 2

    2. I don't know much but I know the displacement formula is deltax=x_f - x_i

    3. I did 25/13=1.92 and -5.5/0.65=-8.46. I know this is wrong but this is my work and I hope to find an answer
  2. jcsd
  3. Sep 20, 2015 #2


    Staff: Mentor

    You have two objects, both moving at constant velocities.
    Write an expression for the distance Object 1 covers.
    Write an expression for the distance Object 2 covers.
    What is the total distance the two objects cover?
    At what point does Object 1 collide with Object 2?
  4. Sep 20, 2015 #3


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    Homework Helper

    Is this a 1D problem? Object 1 is moving downward and Object 2 is moving upward (no gravity?), right?
    The -5.5 / 0.65 = -8.46m gives you how far Object 1 moved in the time. So by deductive reasoning, you should know how far Object 2 travelled in the same .65 seconds.
  5. Sep 20, 2015 #4
    you already mention that they collide 0.65s after starting........you again ask when they both collide........I think the question.........where they collide........how far they will collide from the starting point. If the question is that,,,,,,,,,you need to find out their displacement in .65s
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