Dave Liquorice wrote:
On Thu, 07 Jan 2010 08:51:28 +0000, The Natural Philosopher wrote:

http://www.4x4abc.com/ML320/ml_chainss.html
If you have a steady hill, and conditions aren't changing what
makes
you stop after X meters without chains and double it with?
O level mathenmatics shpould be all you need dave.

If you are moving you are moving and will stay moving unless
somthing
changes.

I must be missing something.


First sensible statement you have made.

With nothing changing, like condition of the snow pack, the gradient,
the power out from the engine, speed of travel etc what is to stop
you?


The speed of travel is changing if you slowly come to a halt.


Once on the hill and moving what alters the grip at 30' further on
compared to 60' further on?


nothing needs to.

If you can apply X amiunt of grip over Y distance, starting at Z kinetic
energy, the total energy you have to climb the hill is Z+X*Y

If you have grippier chains, its Z+2X*Y

If the actual thrust from the non chained tyres isn't enough to get
started up the hill from a stop, you are screwed there anyway.

The key is you hit the hill moving..if the thrust is not enough to
maintain speed up the hill, you will eventually stop at a distance
governed by the above. If you have more grip, the distance will be
longer, and if its enough to clear the crest, you are home and dry.