Related Rates Problem: Two cars start moving from the same point. One travels south at 40 mi/h and the other travels west at 30 mi/h. At what rate is the distance between the cars increasing three hours later?

Answer 1

after t hours,
car One has traveled 40t miles
car Two has traveled 30t miles

Using the Pythagorean Theorem, the distance between the cars is 50t miles.

Looks like the distance is growing at a constant 50 mi/hr. No calculus even needed.