At noon, ship A is 150 km west of ship B. Ship A is sailing east
at 35 km
h and ship B is sailing north at 25 km
h. How fast is
the distance between the ships changing at 4:00 P.M.?
The Attempt at a Solution
I did it using geometry and related rates and got 21.5 which was the answer
but I when I try to do it using relative velocity it doesnt work:
I am taking the first ship initial location as the origin
ra/b=0+35ti - 150i+25tj
ra/b=(35t-150)i + 25tj
dr(a/b) /dt = 35i+25j
and the magnitude is the way more than 21.5
I feel like I am doing something really wrong or setup the problem wrong.