Acceleration/Velocity Problem

1. Jan 23, 2008

ian_durrant

[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. Jan 23, 2008

Shooting Star

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

3. Jan 23, 2008

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

Last edited: Jan 23, 2008