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!

Homework Help: Need help Projectile motion after breaking in two pieces

  1. Apr 16, 2009 #1
    1. The problem statement, all variables and given/known data
    An object is launched from earth as a projectile. At the top of its trajectory the object breaks into separate pieces at a horizontal distance 300m from the launch point. One piece has 1/4 of the mass of the initial object and the other piece has 3/4 of the mass of the initial object. The smaller piece falls straight to the ground while the larger continues its motion.

    At what horizontal distance from the launch point does the larger piece land?

    2. Relevant equations
    Do I need to use a projectile motion equation?
    M1 = 1/4m
    M2 = 3/4m
    Vy = 0 m/s

    3. The attempt at a solution
    I know that both pieces will hit the ground at the same time b/c of 1-D kinematics.
    I'm so lost but here's an attempt:
    For 1/4m = M1
    (M1)gh = 1/2mv^2
    (1/4m)gh = 1/2(1/4m)v^2
    Okay now I don't have height or anything??
  2. jcsd
  3. Apr 16, 2009 #2


    User Avatar
    Homework Helper

    Maybe you are making it too complicated?

    If it didn't break apart the whole thing would land another 300m further on wouldn't it? So when it breaks apart where does the center of mass end up? If you guessed 300m I think that would be a good guess. So ... if the center of mass is at 600m and the 1/4 piece is at 300m mark where would you look for the 3/4 piece?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook