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Adding and Subtracting vectors; Finding change in velocity

  1. Mar 31, 2013 #1
    1. The problem statement, all variables and given/known data

    A batsman hits a cricket ball travelling towards him at 30m/s over square leg at 50m/s. If the cricketer is facing north and square leg is west of him, what is the change in velocity of the ball?

    2. Relevant equations

    Δv= Final velocity subtract initial velocity.

    3. The attempt at a solution

    I've attached a picture of my working, so you might be able to see where I've gone wrong. From this diagram, I got correct the final "speed" but not the direction. My answer was Δv=58m/s N59°W, but the answer given says the direction should be W31°N.
    I got my answer through tan-1(50/30) or tan-1(opposite over adjacent). To get the answer given, you would have to (by my reckoning) use adjacent over opposite, which doesn't seem to be right. Do I have θ in the right place? And, if so, why?

    Thanks for the help :)
  2. jcsd
  3. Mar 31, 2013 #2
    Aren't they the same?
  4. Mar 31, 2013 #3
    ... Are you serious?? Wow, I'm feeling kind of dumb now... Thank you though!! :D
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