2 items reaching same Velocity

Question

One train starts from rest and has an acceleration of 0.8 m/s2. A second train has an initial velocity of 14.3 m/s and a retardation of 0.5 m/s2. After how many seconds are they moving with the same velocity ?

Answer 1

Their initial velocities are 14.3 m/s apart ( 0 vs 14.3 m/s).

Their accelerations are 1.3 m/s^2 apart ( 0.8 vs -0.5 m/s^2) so that means their velocity should be getting closer by 1.3 m/s every second. 14.3/1.3 = 11 seconds.

Another way to approach this is to make a table or graph each train's velocity over time using one of the kinematic equations, V = Vi +at.