1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Angular momentum in projectile motion of rock of mass

  1. Apr 19, 2010 #1
    1. The problem statement, all variables and given/known data

    A rock of mass 55.0 g is thrown with initial horizontal velocity v_x = + 32.00 m/s off a building from a height of 29.00 m. Take UP to be the +y direction. You will need to calculate the angular momentum of the rock about the line along the edge of the roof as a function of time.

    Find the angular momentum of the rock about the line along the edge of the roof at 0.28 s.

    2. Relevant equations

    L = r*m*v

    3. The attempt at a solution

    to find the distance traveled in .28 seconds

    d = 32m/s(.28) + .5(9.8m/s^2)(.28^2)
    d = 9.344 m

    then L = r*m*v

    L = 9.344(.055kg)(32m/s)

    I know this is wrong but i am not sure how else to go about this problem :(

    thank you for any help
     
  2. jcsd
  3. Apr 20, 2010 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    The angular momentum is a vector product:

    [tex]\vec L = m \vec r \times \vec v [/tex]

    For motions in the xy plane, L has only z component and it is

    [tex] L = m ( x v_y - y v_x ) [/tex].

    Determine the x, y coordinates of the projectile as function of time with respect to the edge as origin, and the x and y components of its velocity too, and substitute in the above expression for L.

    ehild
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Angular momentum in projectile motion of rock of mass
  1. Projectile Motion rock (Replies: 5)

Loading...