Relative Velocity & Train Crossing

Kinematics · ch03-motion-in-a-straight-line

Compute relative speed and time of crossing for two trains.

Controls

Velocity of A (east+)20 m/s

Velocity of B (east+)-10 m/s

Length of A200 m

Length of B100 m

Live values

v_{AB} = v_A - v_B

|v_{AB}|

t = (L_A + L_B) / |v_{AB}|

Try this: Make vA and vB opposite signs to model head-on motion — relative speed becomes the sum of magnitudes.