1. The problem statement, all variables and given/known data An elevated train on a track 30.0 m above the ground crosses a street (which is at right angles to the track) at the rate of 20.0 m/s. At that instant, an automobile, approaching at the rate of 30.0 m/s, is 40.0 m from a point directly beneath the track. Find how fast the train and the automobile are separating 2.00 seconds later. 2. Relevant equations No equation was given. 3. The attempt at a solution [tex] dz/dt = 20 m/s [/tex] [tex] dx/dt = 30 m/s [/tex] [tex] h^2 = x^2 + y^2 + z^2 [/tex] [tex] h^2 = 40^2 + 30^2 + 20^2 [/tex] [tex] h^2 = 54 dh/dt [/tex] [tex] h^2 = x^2 + 30^2 + z^2 [/tex] [tex] 2h(dh/dt) = 2x(dx/dt) + 0 + 2z(dz/dt) [/tex] [tex] 2(54) dh/dt = 2(40) dx/dt + 0 + 2(20) dz/dt [/tex] [tex] 108 dh/dt = 80 dx/dt + 40 dz/dt [/tex] *don't know what to do next* Am I doing this right so far? Any suggestions are really appreciated, thanks a lot!