# 2D kinematic motion collision

This is not for an assignment as much as my own edification, but as it is a homework-style question, I thought this would be the best place. If not, I apologize.

## Homework Statement

Given two hockey pucks of radius R1 and R2 on a frictionless, infinite level plane, located at (X1,Y1) and (X2,Y2) and moving at constant velocities (Vx1,Vy1) and (Vx1,Vy1) respectively:

1) Determine whether or not the two pucks will ever collide.
2) How long in seconds until they collide?

## Homework Equations

D = ([X1-X2]2+[Y1-Y2]2)
dX = Vx*dt
dY = Vy*dt

## The Attempt at a Solution

It seems obvious to start at figuring out if they are currently colliding, which is if the distance between them is less than their combined radii: D = ([X1-X2]2+[Y1-Y2]2) < (R1 + R2)

So I need to figure out how the position and velocity can be fit into this. I know the kinematic equations for position with respect to velocity and time are dX = Vx*dt and dY = Vy*dt, but I can't seem to figure out where to go next. It seems like it should be simple.

Thanks in advance Last edited: