D: Yael, why are you limping?

Y: Someone on the bus stepped on foot. Why does getting stepped on by a high heel      seem to hurt so much more than getting stepped on by any other shoe?

D: High heels don't seem to hurt more: they really do hurt more, and here's why. In      physics, pressure depends on the amount of force acting on a surface and on the size      of the surface. The smaller the surface, the greater the pressure. Let's say that the      woman who stepped on your toe weighs 120 pounds. If she had been wearing flat      shoes, you would have felt the force of 120 pounds spread out over the whole heel      of the shoe, maybe around 4 square inches. So the pressure would have been 120      divided by 4, or 30 pounds per square inch.

     But when she steps on you with a high heel, the whole 120 pounds of force is      concentrated on a heel that is maybe one eighth of one square inch in area. Now the      pressure of her step is eight times as much, or 240 pounds per square inch instead of      30 pounds per square inch. Of course, it hurts more.

Y: I guess it works the other way, too. Spike heels are painful to wear because your      weight is all on the spike and on the ball of the foot so the pressure is much greater      on these points than in running shoes, where your weight is spread out over the      whole bottom of the foot.

D: I guess if she had worn flat shoes, it would have been more comfortable for her and      for you.  

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