How fast do I need to be going to kill my Kerbals?

While crash landing on Kerbin, I managed to slow myself down to around 10m/s before hitting the water, and they still died.

How fast do you need to land to kill a Kerbal and does anything else (like type of command pod) affect it?

Solution 1:

The command pod does matter, as well as what parts of your spaceship hit the ground first. The maximum impact speed that your capsule can sustain (in m/s) is given as the impact tolerance in the item card when constructing your ship:

I suspect, but haven't tested that this holds true for all other available parts. As proof, for the pods though, I did a series of drop tests on the launch pad. In each case, I tried to achieve the maximum impact speed possible without the pod exploding:

It's a little hard to see, but all the impact speeds are just below the value given for the impact tolerance on the respective info cards.

Now, as for why your capsule didn't survive. Ironically, I believe your capsule would have survived if you had crashed into terrain at that speed. The rockets and fuel tank on the bottom of your capsule would have exploded crumpled, reducing the speed that your capsule would have hit at. But for some reason, this doesn't seem to always happen when hitting water.

For further testing, my assertion that the impact tolerance == max impact speed should be verified for more (all) standard parts, and the difference between a vessel hitting land and water should be tested.