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Homework Help: What is the difference between above and below the horizontal?

  1. Oct 22, 2014 #1
    1. The problem statement, all variables and given/known data
    Some of the questions in my homework list the velocity either above or below the horizontal. Im confused as to what the difference is.

    This is the question:

    "A child sitting in a tree throws his apple core from where he is perched (4.0 m high) with a with a velocity of 5.0 m/s [35 DEG above the horizontal], and it hits the ground right next to his friend.

    Does that mean it's a 35 DEG angle or does it mean its a 55 DEG angle?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 22, 2014 #2


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    Staff Emeritus
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    Imagine a horizontal line is drawn from the child extending outward.

    As the child throws the apple core at an angle above the horizontal, there is a vertical component of the velocity which is positive upward.

    If the core is thrown at an angle below the horizontal, the vertical component of the velocity is negative downward toward the ground.

    Angles are measured using the horizontal line as the reference, so something which is thrown horizontally has an angle of zero degrees.
  4. Oct 23, 2014 #3
    Thank you for clarifying :)
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