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Vector Question any suggestions?

  1. Oct 10, 2006 #1
    A plane flies 483 km east from city A to city B in 45.0 min and then 966 kim south from city B to city C in 1.50 h. For the total trip, what are the magnitude and direction of the plane's displacement, the magnitude and direction of its average velocity, and its average speed?
     
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  3. Oct 10, 2006 #2

    Hootenanny

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    It may be helpful to draw a diagram. Some pythag and trig may also be required...
     
  4. Oct 10, 2006 #3

    radou

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  5. Oct 10, 2006 #4
    Would this be correct:

    I calculated r the distance between points A and C by r = (483 km) + (- 966 km) to get - 483 km
    So the planes magnitude was 483 km in the negative direction, or south east. Is this correct?
     
  6. Oct 10, 2006 #5
    Basic physics help

    A plane flies 483 km east from city A to city B in 45.0 min and then 966 kim south from city B to city C in 1.50 h. For the total trip, what are the magnitude and direction of the plane's displacement, the magnitude and direction of its average velocity, and its average speed?

    Would this be correct:

    I calculated r the distance between points A and C by r = (483 km) + (- 966 km) to get - 483 km
    So the planes magnitude was 483 km in the negative direction, or south east. Is this correct?
     
  7. Oct 10, 2006 #6

    radou

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    Nope, use Pythagoras's theorem to calculate the magnitude of the total displacement of the plane.
     
  8. Oct 10, 2006 #7
    ok.. so i used pythagorean theorem and got this:

    r = 1080.020833 which i'll round to 1080 for 4 sig figs.

    Now finding r gave the the magnitude would i use the tan formula to find direction???
     
  9. Oct 10, 2006 #8

    radou

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    Exactly. By the way, the 'arrow' points from A to C.
     
  10. Oct 10, 2006 #9
    Basic physics help

    ok.. so i used pythagorean theorem and got this:

    r = 1080.020833 which i'll round to 1080 for 4 sig figs.

    Now finding r gave the the magnitude would i use the tan formula to find direction???


    now i found the angle to be = tan-1 (966/483) and got 63.4 * but how do i know what direction its in???
    If i draw the diagram on the cartesian plane i get the final location of the plane to be in the -y +x coordinate, so it would be in the south east direction??? am i right???
     
  11. Oct 10, 2006 #10
    based on your last reply, whats the definition for magnitude?
    b/c now i've got to find magnitude and direction for average velocity and then average speed
     
  12. Oct 10, 2006 #11

    radou

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    Yes, you're right. Again, look at the vector addition rule I linked somewhere above, it should make everything clear.
     
  13. Oct 10, 2006 #12
    Basic physics help

    Alright, so to find the magnitude and direction of the plane's average velocity i used the vave = delta r/delta t formula to find average velocity for vx and vy and then i used pythagorean theorem to find v and i got 910.8 km/h... does that make any sense? Now im assuming the direction would be exactly the same as before. And how do i calculate average speed?
     
  14. Oct 10, 2006 #13

    radou

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  15. Oct 10, 2006 #14
    Alright so based on the website you provided and my notes i calculated the average speed to be 644 km/h and the average velocity to be 214.7 km/h in the south east direction.

    v = (483 + 966)/2.25 = 644 km/h

    vave = (966-483)/2.25 = 214.7 km/h south east

    What do you think??
     
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