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Projectile motion of a flying object

  1. Jan 26, 2015 #1
    1. The problem statement, all variables and given/known data
    an object is thrown horizontally off a cliff with an initial speed of 7.5m/s. The object strikes the ground 3 sec later
    what is the horizontal velocity after 1.5 sec
    2. Relevant equations


    3. The attempt at a solution
    i don't know how to start this problem without an angle given
     
  2. jcsd
  3. Jan 26, 2015 #2

    SteamKing

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    What does 'horizontally' mean to you?
     
  4. Jan 26, 2015 #3
    im not really sure what it is, I don't know any equations to solve this problem,
     
  5. Jan 26, 2015 #4

    SteamKing

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    Well, if you have a dictionary you could look up the definition of 'horizontally'. You can probably find some dictionaries online if you are diligent.

    (Hint: 'horizontally' and 'vertically' are often used in these types of projectile problems. You should become familiar with their definitions.)
     
  6. Jan 26, 2015 #5
    i think it is the same as the initial speed given so 7.5m/s, is that right?
     
  7. Jan 27, 2015 #6

    SteamKing

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    The initial speed is the initial speed, no more, no less.

    You were originally looking for the initial angle at which the projectile was thrown. Knowing the definition of 'horizontally' provides that angle, no more, no less.
     
  8. Jan 27, 2015 #7
    Hi rosa. A ball is thrown horizontally--- this means the ball is thrown at an angle of 0 deg. with the X-axis.
    55.png
    What are the forces acting on the ball in X-direction (or horizontal direction)? What is the acceleration of the ball in horizontal direction?
     
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