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Homework Help: I'm hoping someone could check my answers.

  1. Apr 1, 2008 #1
    In 2.0 min., a duck travels 22m [36deg N of E] then paddles 65m [E 25deg S] determine
    i) total distance, ii) average speed, iii)tatol displacement iv) average velocity.

    Relevant equations: v%=d/t (for velocity and speed)

    i) total distance 22m+65m=87m
    ii) v%=87m/120s
    v = 0.725m/s
    iii) let N&E be positive NS comp. 22sin36deg=12.93, 65sin25deg= -27.47, 12.93-27.47= -14.54or 14.54
    EW comp. 22cos36deg=17.79, 65cos25deg=58.91, 17.79+58.91= 76.7[E]

    d^2=14.54m^2+58.91m^2
    d=78m
    iv) v=78m/120s
    v=0.65m/s [E 79.3deg S]

    Thanks for any help
    Cheers!!!
     
  2. jcsd
  3. Apr 1, 2008 #2
    in iii) you write d^2=14.54m^2+58.91m^2 wich should be d^2=14.54m^2+76.7m^2, but you have the correct final answer.

    in iv) the direction is wrong. [E 79.3deg S] meant "79.3 degrees south of east" in the rest of the problem, so this is directed nearly south. the velocity was 76.7 meters to east and 14.54 meters south in 120 seconds.
     
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