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Homework Help: Check my answers please

  1. Oct 16, 2005 #1
    1. For an object movin along a trajectory, the horrizontal acceleration of the object _____as the position changes.

    increases- decreases- (always zero)*<my answer in parenthases

    2. In trajectory motion the intitial horizontal velocity is ------------ the final horizontal velocity

    greater than- less than- (equal to)*

    3. When an object it launched from the ground, the acceleration in the y direction is___.

    zero- (constant)* increasing- decreasing-

    7. If an object is launched at an angle of 90 degrees at a velocity Vo the velocity in the x -direction is _____

    Vo- 0- cannot be determined from information given- (Vo sin0)-

    8. Three identical balls are dropped from the same hight with differents speeds. which of the following is incorrect

    same vertical distance
    same horizontal distance
    (same time to reach the ground)

    9. When a projectile is launched horizontaly from a height the initial velocity in the y direction is------

    zero constant ( zero and constant) neither

    10. an airplane at constant horizontal velocity over level ground releases a package which falls to the ground as a projectile when the package hits the ground it is

    in front of the place
    behind the plane
    (directly below the plane)
    cannot know without knowing the planes height

  2. jcsd
  3. Oct 16, 2005 #2
    #7. i think the answer is zero although vo sin 0 is zero because it is actually vo cos 90.
    #9. i think the answer is neither because its initial velocity is zero but increasing with time because of gravitational accerelation.
  4. Oct 16, 2005 #3
    Thats the right approach, but theres no reason that can't be determined! If you throw something straight up, how far to the right/left/front/back does it go? What is [itex] \sin 0 [/itex]?

    If it is launched purely horizontally, there is no velocity in the y direction. But, ofcourse, the object will start falling.. which means what happens to the y velocity?

    The rest are good!
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