Related Rates - Two Trains

HELP
 

One train travels west toward Denver (the origin) at 2 mi/min (120 mph), while another train travels north away from Denver at 1.5 mi/min (90 mph). At time `t = 0` (here `t` is in minutes) the first train is 20 miles east of Denver and the second train is 10 miles north of Denver.

Explore

  1. Calculate the rate at which the distance between the trains is changing when `t = 0`.
  2. Calculate the rate at which the distance between the trains is changing when `t = 10`.
  3. Look at your answer to the previous question and see how it relates to the situation modeled in the applet. Could you have guessed your answer without doing any calculation?