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Re: [Phys-L] train stopping distance




On 2016, Jun 24, , at 12:38, John Denker <jsd@av8n.com> wrote:


The coefficient of friction for steel-on-steel is on the order of 0.5,
so when you see an acceleration of 0.02 Gee you know they're not trying
very hard.


If I were the “engineer” of a passenger train, I’d make a quick decision as to the conflicting result(s) of a one g stop and the collision.


bc points out that passengers ina train aren’t using seat belts.


p.s. Also what about “floating" luggage?



On 2016, Jun 24, , at 12:38, John Denker <jsd@av8n.com> wrote:


Typical fasteners (for holding rails to the sleepers) look to me
like they're designed to constrain movement in every direction
/except/ longitudinal. There must be ways of transferring
longitudinal momentum to/from the earth, but the details don't
seem particularly obvious.
__________

Despite not having read the references, I’ll …

Intuitively the coefficient of f. steel on wood (in Europe the sleepers are sometimes concrete.) is greater than the steel-steel 0.5. So the prob. is sleeper movement on (in) the ballast. There the friction is > 1, I think. I judge this from the German buildings on sand for gun emplacements. (gud for vibration isolation also)

— Not a bad science faire project, no? — .