# Urgent HELP A problem on 2D kinematics

1. Sep 26, 2008

### Kudo Shinichi

Urgent!!!HELP!!!A problem on 2D kinematics

1. The problem statement, all variables and given/known data
A flock of Canada geese directly fly above Kingston is flying due north at a speed of 25km/hr. A second flock directly above Gananoque, 30km to the east of Kingston, is flying in a northwesterly direction at the same speed. Assume there is no wind where the geese are flying.
a)What is the distance of closest approach between the two flock
b)How long does it take to reach this point?
c)What are the position vectors of the two flocks relative to Kingston at this instant of time?

Can anyone help me? thank you very much.
3. The attempt at a solution
The formula for distance is ((30-25t/sqrt(2)) - 0)^2 + (25t - 25t/sqrt(2)) ^2 = 625t^2(3/2 - sqrt(2) + 1/4) -25 t sqrt(2) + 900
Derivative: 625t (3.5 - sqrt(2)) -25 sqrt(2). =0
t = 1/25(3.5 - sqrt(2)).

2. Sep 27, 2008

### Staff: Mentor

Re: Urgent!!!HELP!!!A problem on 2D kinematics

Looks like the right approach.
Looks good.
Redo this step. I get a different answer.