Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Projectile motion

  1. Feb 19, 2006 #1
    A boy throws a ball into the air at an angle to the horizontal. The ball reaches a vertical height of 8.0m and travel a horizontal distance of 16m before being at the same vertical position as at the point of release
    A. what is the magnitude of the vertical velocity component of the ball as it is thrown?
    B. What is the time of the flight of the ball?
    C. What is the horizontal velocity component of the ball at its point of throwing?
    d. What is the speed of the ball at this point of release?
  2. jcsd
  3. Feb 19, 2006 #2


    User Avatar
    Gold Member

    You need to show some work or we can't help you.
  4. Feb 19, 2006 #3


    User Avatar
    Homework Helper

    Find the time to fall down from the top first. the time to rise is the same.
    That's (B).
    Then do (c) or (A).
  5. Feb 19, 2006 #4

    A) The maximum height of the ball is [tex]H=\frac{v_{0y}^2}{2g}[/tex]
    [tex]\Longrightarrow v_{0y}=\sqrt{2gH}[/tex]

    B)The vertical component of the ball [tex]v_y=v_{0y}-gt[/tex]

    The ball reach the max.hight when [tex]v_y=0\Longrightarrow t=\frac{v_{0y}}{g}[/tex]

    The time of the flight of tha ball is [tex]\Delta t=2t=\frac{v_{oy}}{g}[/tex]

    C) The horizontal velocity component of the ball at its throwing point is [tex]v_{0x}=\frac{L}{\Delta t}[/tex]

    D) The speed of the ball at release point is [tex]v_0=\sqrt{v_{0x}^2+v_{0y}^2}[/tex]
    Last edited: Feb 19, 2006
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook