1. Not finding help here? Sign up for a free 30min 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!

Projectiles physics problem - due tomorrow ;_;

  1. Nov 16, 2006 #1
    hey everybody, i would really appreciate a little help with this.

    I have a projectile, labeled zero, with mass m and velocity V. it travels in a parabolic motion until it reaches its apex, at which point it divides into two equal pieces, 1 and 2, with mass m/2 and m/2. Each of these pieces splits off with a velocity theta degrees from the horizontal.

    Now, i need to determine V1 initial and V2 initial in terms of V, theta, and unit vectors i^ and j^.

    Any help at all would really be appreciated - i have AIM(antigravityjesus) and MSN (antigravityjesus@hotmail.com).
    Thanks!
     
  2. jcsd
  3. Nov 16, 2006 #2
    oh, forgot to say, this is the third part - i already found Delta K / K initial and solved some change-in-K relative to Theta equations.

    The problem is, if i sub kinetic energy = kinetic energy into conservation of momentum, i get V = V.

    Can i somehow use my Delta K/K equation here? im at a loss.

    Thanks.
     
  4. Nov 16, 2006 #3
    okay, this is what ive done:

    1/2 m V^2 = 1/2 m 1/2 v1i ^ 2 + 1/2 m 1/2 v2i ^ 2
    which equates to
    V^2 = v1i^2 + v2i^2 / 4


    mV = mv1/2 + mv2/2
    which equates to
    V = (v1+v2)/2
    V^2 = (v1^2 + 2v1v2 + v2^2)/4
    ... which doesent directly equal v1i^2 + v2i^2 / 4 ... neat. let me see if i just accidentally solved something!

    The problem is, i dont have any equations with theta in it.
     
  5. Nov 16, 2006 #4
    nope, just gives me v1=0 and v2=0. darn.
     
  6. Nov 17, 2006 #5

    OlderDan

    User Avatar
    Science Advisor
    Homework Helper

    Kinetic energy cannot be conserved in this process. It is first a conservation of momentum problem. If the angle θ is given, or your answers are supposed to be expressed in terms of θ then all you need is conservation of momentum.
    You can't find the change in kinetic energy without using momentum conservation to find the velocites, so I really don't get what you are saying here.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Projectiles physics problem - due tomorrow ;_;
Loading...