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!

Max distance betw 2 retarding bodies moving towards each other,so that they meet.

  1. Apr 6, 2008 #1
    1. The problem statement, all variables and given/known data
    Two bodies move in a straight line towards each other at initial velocities v1 and v2 and with constant retardation a1 and a2 respectively at the initial instant. What is the max initial separation between the bodies for which they will meet during the motion?

    (sqr -> square of , root ->square root of)
    Options:
    a) sqr(v1)/a1 + sqr(v1)/a2
    b) sqr(v1+v2)/2(a1+a2)
    c)v1*v2/root(a1*a2)
    d)sqr(v1)-sqr(v2)/(a1-a2)


    2. Relevant equations

    sqr(v) = sqr(u) + 2as


    3. The attempt at a solution

    Let s1 = Distance travelled by object1 before it stops at last
    and s2=Distance travelled by object 2 before it stops

    0 = sqr(v1) - 2*a1*s1
    s1= sqr(v1)/2*a1
    s2=sqr(v2)/2*a2

    Max dist=s1 + s2

    However, this answer does not match with any of the options above. According to the book, the correct answer is option b.
    Help!
     
  2. jcsd
  3. Apr 7, 2008 #2
    My answer doesn't match too.

    I did it like this:

    [tex]t=\frac{v_{1}}{a_{1}}=\frac{v_{2}}{a_{2}},[/tex]

    [tex]s_{1}=v_{1}t-\frac{a_{1}}{2}t^{2}=\frac{v_{1}^{2}}{a_{1}}-\frac{v_{1}^2}{2a_{1}}=\frac{v_{1}^{2}}{2a_{1}},[/tex]

    [tex]s_{2}=v_{2}t-\frac{a_{2}}{2}t^{2}=\frac{v_{2}^{2}}{a_{2}}-\frac{v_{2}^2}{2a_{2}}=\frac{v_{2}^{2}}{2a_{2}},[/tex]

    but the sum of the last two expressions doesn't match with the (b) option, for which you say that equals to:
    [tex]\frac{(v_{1}+v_{2})^{2}}{2(a_{2}+a_{2})}.[/tex]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Max distance betw 2 retarding bodies moving towards each other,so that they meet.
Loading...