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Homework Help: Questions with many unknowns

  1. Oct 16, 2008 #1
    A basketball player tries to make a half-court jump shot, releasing the ball at the height of the basket. Assuming that the ball is launched at 54.0°, 14.0 m from the basket, what speed must the player give the ball?

    There are a lot of unknowns and i dont know where to start

    any help?
  2. jcsd
  3. Oct 16, 2008 #2
    Well, if the ball is released at the height of the basket it means that you have to find the initial velocity that will result in the ball returning to its original y position over a horizontal distance of 14 metres.
  4. Oct 16, 2008 #3
    There is only one unknown: the speed of the ball.
    Note that the ball is released at the height of the basket....
  5. Oct 16, 2008 #4
    Don't be intimidated by multiple unknowns - all it means is a few more steps.

    Start by determining what you know. Don't worry if you have to define one thing (such as velocity) in terms of another unknown (such as time).

    In this case you are looking for velocity. Since you have an angle, you can define it by its vertical and horizontal components. You know the total distance it is traveling vertically (it starts and ends at the same height) and you know the horizontal distance it travels (given as 14.0 m). You also know the acceleration in each direction (a = g vertically, a = 0 horizontally). From this, you should be able to develop two equations with two unknowns in each (make sure they are the same unknowns). Solve one equation for one unknown in terms of the other, then substitute that into the other equation. You now have only one unknown and can solve for that.

    Hope this helps get you started.
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