ByMark Newton, writer at
Movie Pilot Associate Editor. Email: [email protected]
Mark Newton

So what would happen if you really did wear glass slippers to a swanky ball? Would you win the affections of an, admittedly rather shallow, prince or will you simply end up spending the night in the Accident and Emergency wing of your local hospital?

Well, to answer the question of whether glass slippers are an actual viable form of footwear, Gizmodo looked to Antariksh Bothale - a Mechanical Engineering masters graduate with a penchant for answering life's really big engineering problems.

Could a Glass Shoe support Cinderella's Weight?

Now, to answer this question, Bothale had to work on the basis of a few assumptions. Namely that the size and scale of the glass slipper was probably similar to that of a classic high-heeled shoe (which is about 0.015m²), and that Cinderella probably weighed somewhere in the region of 50kg.

Now, generally, pressure and weight is not uniformly applied across a shoe - with the toe area often taking the brunt of the weight. But for his general calculation, Bothale discounted this fact. Instead, he theorized that Cinderella's shoe would have to tolerate a force of 500 Newtons - as it is 10 Newtons to each kilogram.

Using this information, he can calculate what the compressive stress would be on the shoe. To work this out he used an impressive looking equation, which he doesn't actually bother to explain. It looks like this:

This means Cinderella will apply 33 kilopascals of pressure onto the glass shoe. The yield strength of ordinary glass is somewhere in the range of 50 megapascals - meaning the glass shoe should comfortably sustain Cinderella's weight. In fact, the glass is so strong, we do not even need to factor in the uneven distribution of her weight.

But is Cinderella Safe?

So does this mean Cinderella can pirouette the night away? Well, not entirely.

Cinderella could comfortably stand in the glass slippers, but doing anything else would be flirting with danger.

In particular, Bothale suggests the pressure applied to the heel of shoe when Cinderalla is walking could result in disaster. Generally, we place our heel down first when we walk, which means Cinderella will be applying a lot of force (while at an angle) to the heel. He concludes the shoe could still maintain her weight, but she would have to be careful so as to not push it beyond its maximum bending stress allowance.

But there is another danger. Could the friction between the glass shoe and a stone floor be so low as to cause Cinderella to slip?

Bothale states the friction coefficient for glass on stone is about 0.42 (that number doesn't mean anything to me either), which he suggests is within acceptable levels. Although Cinderella should probably take it easy.

Were Cinderella's Shoes Even Made of Glass?

Of course, all of this rides on one over-arching supposition - that Cinderella's shoes were actually made of glass.

It is now believed by some that the original story of Cinderella contained no reference to glass slippers. Instead, it is claimed she wore fur slippers.

The confusion originates from two extremely similar sounding words in Cinderella's original language - French. When the tale was first told in heraldic old French, it was claimed her shoes were made of 'vair' - which is the Old French word for fur. This word is pronounced exactly the same as 'verre' - which is the modern French word for glass.

Considering slippers were traditionally made of fur, this does make a little bit more sense. Although fur slippers aren't quite as alluring.


What do you think? Were Cinderella's shoes made of glass or fur?

Source: Gizmodo


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