Low Mass Colliion

[Blue]

It would probably cause a pretty serious injury to be hit by a feather traveling at 2.5km/s.

I'm thinking about low mass collisions for a pretty weird reason, and I can't actually think of how the physics would work very well for some reason. Would it be survivable for a human to be hit by the broadside of a solar sail or other extremely thin sheet of material traveling at a high speed like the one I suggested; is spider-silk insubstantial enough? Or would it depend on the tensile strength of the impacting material, more than its mass?

[Ravenchant]

Hm. Interesting question...a feather weighing half a gramm would, at 2.5 km/s relative to you, carry about 1,5 kJ of kinetic energy. Wikipedia tells me that's equivalent to 2 Magnum revolver rounds.

If it hit you with the pointy end, you would probably end up with a quill-shaped hole in your body. No idea what would happen to the rest of the feather, though. If it hit with its side, there's always the possibility of blunt trauma even if no penetration occurs.

(assuming we ignore spacesuits and similar contraptions, instead exposing our brave volunteer test dummy to the elements)

Edit: regarding solar sails. 10 g/m^2 is a good approximation of their current area density. Let's say your body has a cross-section of 1m^2, slightly more in a spacesuit. If the impact tears, oh, let's say 2m^2 of sail area out, 50 Ns get imparted on you. For a 100kg astronaut, the resulting velocity change will be 0.5m/s^2. I frankly have no idea what to make of this. Chances are better if the material is tensile because instant velocity changes are bad for humans, and you would want to minimise your body area to, well- rip through the material like a bullet.

If the sail doesn't tear, you get accelerated rather quickly and probably get your internal organs reduced to a mush that makes the recovery team vomit in the airlock. So there's that.

Edited September 8, 2014 by Ravenchant

[Blue]

Okay your response finally got me on track.

Spider silk weighs 1.31g/cm³. If we have 1 cubic centimeter uniformly spread out over a sheet 1 micron thick, it comes out to exactly 1 square meter. (100cm * 100cm * 1 micron = 1cm³.)

0.5*1.31 grams * 2500 m/s ² is 4.094kJ of kinetic energy.

Edited September 9, 2014 by Blue