How to safely jump off a moving train (in terms of physics)

Agree, rarely people have to jump from a train moving at full steam. Rhett Allen, assistant professor of physics at the University of Southeast Louisiana, spoke about how to do this and not get severely injured.

Option # 1 - decrease initial speed. If you just jump off a train moving at a speed of 36 km / h, then you will fall to the ground. During the impact, you will have vertical speed as the train is above the ground. When falling, the gravitational force will increase the vertical speed, as if the jump were made from a stationary train. If the height is 1 meter, then the jumper will move at a speed of 4 m / s.

Do not forget that the train is moving, therefore, in addition to the vertical speed of 4 m / s, the jumper moves at a horizontal speed of 10 m / s. In this case, the cause of injury will not be speed, but acceleration.

Just as speed refers to a rapid change in position, acceleration describes how the speed of the jumper changes in m / s 2. There is no “safe” level of acceleration, but as acceleration increases, the risk of injury increases.

To reduce acceleration on impact, reduce the initial velocity. If, for example, the train is moving north at a speed of 10 m / s, then you should run against the movement (inside the train) at a speed of 4 m / s. Thus, due to the relativity of the speed, it will be possible to reduce it to 6 m / s relative to the ground.

Option # 2 - increase the stop time. The ideal option when jumping off a train is to use a sled that will slide on the ground after the jump. Another option is to do somersault at the end of the landing. The most important thing in this case is to stretch the stop time to reduce acceleration.

Afterword

Please note that all of the above is considered by Associate Professor Rhett Allen solely from the point of view of physics. People who practice such tricks in reality recommend completely different methods: for example, a jump in the backward direction, but in a position with their face in the direction of the train. Someone argues that you need to jump back and forth, but also face in the direction of travel.

In any case, we do not recommend anyone to experience all this not for themselves, since the cost of a mistake can be too high.