Is it possible to construct a device on a train, which would enable people to jump off the train at full speed?
It would work by accelerating a person backwards to cancel train velocity, so that they fall down on the platform unharmed.
- It needs to fit on a train car (20 meters)
- Maximum acceleration of 2g (?)
Solution
$$v=\sqrt{2\,as}$$
$$v=\sqrt{40\cdot20}\,\textrm{m/s}\sim100\,\textrm{km/h}$$
So it seems that full speed (~200 km/h) is impossible, but full speed in residential areas is possible, in principle.