Question

Which would hurt more if it hit you- a water balloon dropped from 100 feet or a water balloon dropped from 50 feet? Explain why.

Answer 1

"I don't think any height could cause a death by water balloon! At least, not for a small balloon. Here's my back-of-the-envelope calculation to that effect:
I assumed a spherical water balloon weighing about 1 kg (that is, a few pounds), and after a quick calculation, I worked out that the terminal velocity of the water balloon is about 50 m/s.

How much force does that transfer to the person? Well, the change in momentum will be something less than (mass)*(velocity), because clearly not all of the water will just come to a complete stop on top of your head (most of it will splash and continue going down, right?) Still, to be conservative let's say 2/3 of the mass comes to a complete stop on your head, so the impulse = change in momentum times 2/3:
I = 2/3*(50 m/s)*(1 kg) =33.333 kg m/s

Now, the average force will be I/(time duration of impact. What should we use for the time of impact? I have no idea! But let's come up with a reasonable guess. So, Let's say the impact only lasts for .1 seconds. Or, to make it even scarier, how about .075 seconds.

So, then, the average force will be I/(.075 s):

F = 444.4 Newtons.