Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

Interestingly, in this /r/askscience thread:[1]

1) lots of comments are attributing the jerk felt by occupants to the vehicle suspension. But that isn't the case! The occupants visibly move backwards relative to the car body, but the backwards motion of the car itself should rather have the opposite effect.

2) a commenter contradicts what several commenters here have noticed:

> I wager this has to do with the driver; most drivers I've noticed don't ease up off the breaks when slowing down, and so the 'slowing force' feels like it ramps up along the deceleration profile, up until the point when the car comes to a complete start and there's a 'jerk'.

[1] https://www.reddit.com/r/askscience/comments/20mljk/what_cau...



> The occupants visibly move backwards relative to the car body

The only video linked to in that thread has been removed so I wasn't able to see this, but I will point out that the timing is critical to interpreting this observation. During deceleration, the occupants will move forward relative to the car body so that the car can apply a decelerating force to their bodies (via seat belts or friction against the seats and floor of the car). At some point after the car has stopped, they will necessarily move back to their neutral position. This will have nothing to do with the transient motion of the car when acceleration drops to zero.

I will also note that it is not that difficult to come to a complete stop with no perceivable transient if you ease off the brakes as the car comes to a halt. It's actually a useful skill to cultivate IMHO.




Consider applying for YC's Summer 2026 batch! Applications are open till May 4

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: