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Homework Help: Linear momentum of 2 objects colliding find velocity and angle

  1. Oct 5, 2012 #1
    1. The problem statement, all variables and given/known data
    Some birds of prey, such as the northern goshawk, hunt other birds in midair. Typically, the hawk spots the prey while soaring high above, then dives in for the kill with the deadly grip of its talons. They do not shy away from larger prey, such as ducks and crows. Using the change in linear momentum, we want to estimate the impact on the hawk when completing a successful kill by clawing into the prey, which we take to be an unsuspecting American crow. Use mass of crow
    mC = 452 g,
    horizontal flight of the crow with speed
    vC = 14 m/s,
    mass of hawk
    mH = 915 g,
    flight path in the same plane as the crow but approaching from behind with
    vH = 21 m/s
    and with an angle of
    θ = 74°
    with the horizontal, as illustrated in the side view of the figure below.
    How fast does the hawk move immediately after catching the crow?
    By what angle has the direction of motion of the hawk changed at the impact? Note: American crows take the danger posed by high-soaring hawks very seriously. They are often seen as a group attacking the predator to drive it out of their neighbourhood.

    2. Relevant equations

    3. The attempt at a solution
    Tried using m1v1-m2v2cos(θ)=(m1+m2) vf
    but could not get right answer
  2. jcsd
  3. Oct 6, 2012 #2


    User Avatar

    Staff: Mentor

    Hi studyhard, http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    As you haven't shown your working, there is not much we can examine to see where you may be going wrong. About all I can say is to remind you that these problems are often best worked using horizontal and vertical components, before using Pythagoras.

    Besides showing a diagram with your working, it is always helpful to include the answer you are aiming for, if known.
    Last edited by a moderator: May 6, 2017
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