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: Acceleration/Velocity Problem

  1. Jan 23, 2008 #1
    [SOLVED] Acceleration/Velocity Problem

    1. The problem statement, all variables and given/known data

    In an historical movie, two knights on horseback start from rest 78.0 m apart and ride directly toward each other to do battle. Sir George's acceleration has a magnitude of 0.257 m/s2, while Sir Alfred's has a magnitude of 0.389 m/s2. Relative to Sir George's starting point, where do the knights collide?

    2. Relevant equations

    x= V(0)t+ (1/2)at^2

    Average Acceleration

    Average Velocity

    3. The attempt at a solution

    Ok I'm first of having trouble finding out where to START in this problem. I decided the best move would to use x= V(0) + (1/2)at^2 to find out how long it would take the two horseback riders to cross all 78 m.

    I got t= 24.64 seconds for George
    and t= 20.03 seconds for Alfred

    What I'm having trouble doing now is setting up an equation that would allow me to figureout when the two riders crashed into each other. Any thoughts?
    Last edited: Jan 23, 2008
  2. jcsd
  3. Jan 23, 2008 #2

    Shooting Star

    User Avatar
    Homework Helper

    Hint: the relative accn between the two is the sum of the two accns. Keep George fixed.
  4. Jan 23, 2008 #3
    ahhh good point. thanks to that hint i solved the problem- the answer was it took George 31.03 meters before the collision.

    thanks a bunch
    Last edited: Jan 23, 2008
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook