So About That Glass Slipper…

March 14, 2015

Alright ladies, you know who you are: That girl who will forgo comfort for fashion, especially if it means rocking a great pair of heels on the dance floor. (I am, very occasionally, one of those people. But I always live to regret it.)

Really, nothing beats the costumes for Christopher Wheeldon’s Cinderella. Helloooo gold pointe shoes! (San Francisco Ballet principal Sarah Van Patten in costume, photo by Nathan Sayers for Dance Magazine)

So let’s talk about Cinderella, since I know you all went to see the movie this weekend. She dances, all night, in a pair of glass slippers. Ouch! Can you say blisters?! And do those things have even the slightest bit of arch support?

Fortunately, the smart folks over at Quora set out to determine whether Cinderella’s dainty shoes could actually hold up to a night of dancing. Mechanical engineering, meet dance.

Engineer Antariksh Bothale makes several simplifying assumptions, but he determines that the force of Cindy’s foot on the glass is three orders of magnitude less than the force that glass can sustain. But, that just means that Cinderella is safe to stand around. What about when she actually starts moving? Taking a few more assumptions into account, Bothale determines that the force of Cindy’s step takes her dangerously close to the maximum stress the glass can withstand. He suggests that her shoes be constructed out of a special material called “thermal toughened glass,” which doesn’t sound very stylish but can apparently withstand greater force.

Lastly, what happens when Cinderella runs out of the palace at midnight? There are a lot of variables at play here, and running will apply three to five times the amount of walking force. But suffice it to say that if Cindy’s dress is huge and cumbersome (which we know it is, because have you seen that thing?) and prevents her from taking long strides, she’ll still be within the limits of how much stress the shoes can withstand. Bothale notes that running with a “toe-first foot strike” would solve the problem, but I, for one, know that Cinderella isn’t some dainty prancing princess. She runs like a real girl and that’s the whole point.

Girl with the biggest dress wins. (Still from Cinderella, directed by Kenneth Branagh)