Why do vehicles (especially trains/trams) have this “bump” when they stop completely?

Question

Basically every vehicle has it but in trains/trams is it particularly strong (probably because they have so much mass).

In: Physics

Answer 1

What you are feeling is “jerk” or the change in acceleration. It’s the same sensation when someone suddenly slams on the throttle or brake.

This occurs when a vehicle comes to a stop because brakes only help decelerate when the vehicle is moving. When the vehicle comes to a complete stop, the acceleration goes from {some big negative number} to zero almost “instantaneously” (over a small time); imagine the time it takes for the vehicle to go from 0.1kph and to 0kph.

Jerk = change in acceleration / time.
= {some big number} / {small time}.
= {some bigger number}