HELP ASAP TIMER Three trains are all are moving along a track with the same speed and slam on their brakes. If all three trains have identical coefficients of kinetic friction with the rail surface, which train travels the longest distance to come to a stop?

a
This cannot be determined, without knowing the normal force on the train by the rail.
b
The most massive train.
c
They all travel the same distance in stopping.
d
The least massive train.