what are the conditions under which a human being is unable to react fast enough to dodge a thrown rock?
(try to imagine a duel situation)
conditions could be flight time, distance, velocity of projectile.

how big do you believe is the death circle around a loaded slinger?

watched too much mythbusters episodes.....

So, just to keep the model simple, let's use this set of circumstances:

1. Open room with no obstructions.
2. A 100% Perception Rate of the incoming projectile.
3. Human reaction time (.25 seconds, from: https://backyardbrains.com/experiments/reactiontime )
4. Sling "Muzzle" Velocity of 180km/h (50m/s) (From https://www.youtube.com/watch?v=TVeqTbLTnp0)
5. "Muzzle" Energy of (150g and 50m/s=.5*150*50[squared] = 187.5 J) (From https://en.wikipedia.org/wiki/Muzzle_energy)
6. Energy determines lethality as a simplified version of terminal ballistics.
7. Stone strikes the chest while retaining full muzzle energy.

In this case, the Sling projectile has comparable energy to a .22LR rimfire round. This means it can certainly be deadly, and if we assume there's a hit in the body as the most area presented, we can consider the hit to be very likely disabling.

The deadly band FROM THE INSTANT THE STONE IS RELEASED would be determined by the following equation:
.25 Seconds * 50 Meters = 12.5 meters or 41 feet.

This will shrink as you factor in time for throw preparation time, and so on. However, it will not likely grow.

Also, you can cut out 6 or 7 meters of that, which can be closed to grapple before you can throw, if you follow these rules: https://www.youtube.com/watch?v=ckz7EmDxhtU

Thoughts?

if you can see the slinger, then you can watch the throw and predict the path of the stone.
So it's not entirely down to reaction time.

Like wise with a throwb baseball, knowlege of the pith and pitcher goes a long way towards dodging the ptich.

If you don't see the slinger - say he's behind a mysterious fog bank, but can see you with his magic goggles.
I don't think anyone could dodge fast enough.

     Sling stones come pretty fast.. about 100 mph depending.  In that in your scenario we can see the projectile coming, I'd like at least 50 yards to dodge it.  I am big, easy to hit, and not always super fast.

When we were teenagers, I and my friends threw each other together. The distance was about one hundred meters/ yards. We never saw the stone when it came.
The thrower saw the stone. The recipient did not see.

It was very fun and very dangerous   (And stupid)

There's a great western film with lou gossett junior as a bounty hunter/ gunslinger in.

A teacher finds him to get his help and at one point lou shoots a man in the back.
The teacher is horrified: 'You shot him in the back !'
Lou gives him a lookand says : 'his back was to me.'
That one phrase really sums up the old west, it wasn't romantic. It was dirty, smelly and downright nasty

The point being, warfare is not honourable and the sling is perfectly made as an ambush weapon.
Long range, quiet and almost no way of telling where the missile came from.

So in the mythbusters scenario. Jamie should be hiding, until adams back 'is to him'.

called el diablo - awesome film.

I think it would be harder, rather than easier than the scenario makes it seem. As was said sling stones are hard to see. For me I don't think I would be dodging out of the way of the stone as much as dodging when I saw the slinger actually throw.

If he misses, I might actually end up dodging into his shot but I don't trust myself to track a sling stone and react accordingly over such a short distance.

@timpa what distance are you at in the 2nd video?

watching the 2nd video i think it would be easy to move my limbs out of the way of the stone but not sure about head and torso

don't you think it's wise to run to the opposite direction the sling is turning?