Aship Pis travelling dueEast at 30 km/hand aShip Qis travelling dueSouth at 40 km/h.

Both ships keep constant speed and course.At t=0 they are each 10 kmfrom the point of intersection of their courses and moving towards the point.

Iv found theco-ordinatesofQ relative to P at t=0

---->X=(10,10)km

iv also found thevelocityofQ relative to P----> V= V[Q] -V[P]

-----.V= (0,40) - V(30,0)

----- V= (-30,40)km/h

but im struggling to find thetime at which P and Q are closest to each other...is there anyone that can help??? thankz