Re: How much force does a pillow exert during a pillow fight and is it lethal??

Michael,

After digging around, I've found there isn't a lot in medical literature concerning pillow-fights. The short answer to your question is, "yes, you can seriously hurt someone if you slam a pillow into someone and, as you say, 'knock the crap out of' them'". As a matter of fact, I have a crown on one of my teeth because I was hit in the face with a piece of foam rubber and the resulting impact was enough to fracture a tooth.

The best way to think of this situation is as an inelastic collision - that is, a collision where the two bodies don't rebound from one another after striking together. In this kind of situation, all of the impact energy is transferred from the pillow you're holding into your girlfriend's head.

If I assume that you performed a typical pillow-fight maneuver where you jumped up and slammed down with your whole weight (225 pounds), just the force contributed by your body mass is 225 pounds. In all probability, the force was likely a fraction of thas, as you didn't come to a stop solely through hitting her; very likely a fraction of your weight, say, closer to 25-40 pounds was involved in the impact.

If you add in the swing of the pillow (let's assume you started with the pillow over your head and ended with it directly in front of you at arm's length at the point you hit her head), it is likely the pillow was traveling in the vicinity of 10-15 feet per second at impact. If it stopped within the width of the pillow, the resulting additional force is about 30-45 pounds.

So, even if we only count the pillow, you dropped the equivalent of a 30- pound weight on your girlfriend's head. If you include the minimum guesstimate of the amount of your weight contributing to the impact we have a minimum force of roughly 55 pounds and a maximum about 90 pounds. That kind of force suddenly acting on the top of a person's head can easily cause neck and spine injuries, including disc damage and compression fractures.

Based on these numbers, I think we can safely conclude that your girlfriend is not being a "sissy" and taking time to consider an alternative to pillow-fights is warranted.