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Motion in 1D direction, kinematics

  1. Sep 18, 2009 #1
    1. The problem statement, all variables and given/known data

    A jetliner leaves San Franciso for New york, 4600 km away. With a strong tailwind, its speed is 1100 km/hr. At the same time, a s2nd jet leaves New York for San Francisco. Flying into the wind, it makes only 700 km/hr. When and where do the two planes pass each other?

    2. Relevant equations
    x=x0 + v0T + 0.5at^2
    Vf^2=Vi^2 + 2ad
    Vf= Vi + at


    3. The attempt at a solution

    Basically, from what I know I'm going to make 2 separate sets of equations and somehow equate them, 1 of them in terms of distance, and another one in terms of time. But I don't really know where to start.

    the answer was given to me, they'll be at the same point 2.5 hours later @ 2000km. I dont know how to get this. Please help.
     
  2. jcsd
  3. Sep 18, 2009 #2
    A hint: How long distance has the planes travelled together when they meet?
     
  4. Sep 18, 2009 #3

    rl.bhat

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    When the planes meet, duration of flight time must be the same.
    In that time interval, one plane has traveled x km and the other (4500 - x ) km.
     
  5. Sep 18, 2009 #4
    Well I need to find both the time they meet, and the distance where they meet. But how would I set this up in terms of an equation?
     
  6. Sep 18, 2009 #5

    rl.bhat

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    Both the planes are moving with uniform velocity. What is the relation between the velocity, time and distance?
     
  7. Sep 18, 2009 #6
  8. Sep 18, 2009 #7
    Im not seeing how that helps me at this point. Doesn't this problem have something to do with equating equations or something of the sort?
     
  9. Sep 18, 2009 #8
    I had a bit of a break through, Ok so I found the time at which they will be at the same distance, which was 2.4 hours. I did 4600km/700km/hr= 6.57hr, which is how long the 2nd plane would take to reach the other side, and I also did 4600 km/1100km.hr which is 4.18 hours, which is how long it would take the first plane to reach the other side from where the 2nd plane started.

    But how would I find the distance
     
  10. Sep 18, 2009 #9

    rl.bhat

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    t = x km / (1100 km/h) = (4500 - x) km/( 700 km/h)
     
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