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Alice Springs bridge swing fatality - Sat 13th Nov 17-Nov-2010 At 3:41:06 PM J.C.

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If you have a rope with say 30% dynamic elongation with a static anchor and a fall factor of 1..

-After a 5m fall (which will take a smidgen over a second) you'll be travelling at about 35.6km/h & you'll slow to 0km/h over a distance of about 1.5m

-After a 50m fall (taking a touch over 3 seconds) you'll be travelling at about 112.7km/h but you'll have a much cushier 15m of rope stretch over which to decellerate.

So, on the bigger jump you're traveling about 3 times as fast but you have 10 times as much distance over which to slow down.
Before any physicists get on here, yes I know it's not quite that simple with the deceleration but if I've made some fundamental error please correct me.

Then when we take it to the real world, the majority of the force in a swing is dissipated by inertia redirection (swinging) but I don't have that formula in front of me.