Where Do Knights Collide in a Physics Problem?

[ian_durrant]

[SOLVED] Acceleration/Velocity Problem

Homework Statement

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?

Homework Equations

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

Average Acceleration

Average Velocity

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?

 

[Shooting Star]

Hint: the relative accn between the two is the sum of the two accns. Keep George fixed.

 

[ian_durrant]

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