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Teaching Science with Science Fiction – Weight vs. Mass

The Truth about Pyecraft by H.G. Wells – the difference between Weight and Mass

This post is jam packed with story spoilers so if you would like to first read the story spoiler free here are two links to Google books versions; one from The Strand and the other from the anthology Twelve Stories and a Dream.

In everyday life the difference between weight and mass is not all that important and the terms are often used interchangeably, but in Physics the difference is important.  Weight is the pull of gravity acting on an object while mass is the amount of matter in the object.  Weight changes with a change in gravity due to location, whereas mass does not.  For instance in free-fall the weight of an object is zero Newtons (0 lbs), but it still has mass, and if an object has mass it has inertia.  In practical terms this means that while a 6 ton satellite is weightless in orbit, it will still take a good bit of force to change how it is moving.  So there is no pushing a satellite with a single finger and having it careen into the earth’s atmosphere.  To cement the distinction in the minds of my students I often use a short story entitled “The Truth about Pyecraft”.

“The Truth about Pyecraft” is a short story written by H.G. Wells and was first published in The Strand Magazine in April of 1903 (pg. 425-430) and then subsequently included in the anthology Twelve Stories and a Dream.    It is a humorous story that takes place in a London club and revolves around an odious man named Pyecraft and his desire to lose weight.  Now Pyecraft wants to lose his bulk, but he wants a quick fix.  He enlists the help of the story’s narrator, Mr. Formalyn, who had a particularly interesting great-grandmother.  You see back in India she was something of a witch and was able to brew potions with magical properties.  The recipes for these potions were eventually inherited by Formalyn.

The temptation of an easy solution to his weight problem was too much for Pyecraft who begged and begged for Formalyn to search through those recipes for a potion that would cause him to lose weight.  Formalyn finally agreed and searched the recipes, which was not an easy task because they were in poorly written Hindustani.  Eventually he found one that he was pretty sure would do the trick.

When Formalyn turned the recipe over he warned Pyecraft that his great-grandmother’s recipes do not always work the way one thinks they should.  Pyecraft was so excited that he dismissed any concerns and went about gathering the ingredients written in Formalyn’s translation.  At first it did not work, but after a few weeks and a few tweaks to the translation something finally happened.

Formalyn was enjoying a blissful Pyecraft free day at the club when he received a telegram that implored him to come to Pyecraft’s house.  When he arrived much to his surprise he found the still large Pyecraft floating next to the ceiling. You see Pyecraft did lose weight, but he didn’t lose any mass.  Formalyn perhaps feeling a little guilty started about the task of helping Pyecraft adapt to his new weightless lifestyle.

Pros and Cons of the story

The benefit of using the story is that it gives my students a clear understanding of the differences between weight and mass.  It is a funny story and so my classes tend to pay attention to it without too much fuss.  Even though the Flesch-Kincaid reading level is 4.7 the language of the story can be a little cumbersome especially the parts that are written in dialect, so I would suggest having a fluent reader read the story out loud for classes with reading issues.  Another con for the story and it may be a huge sticking point for some is the fact that the story is about an overweight person and since Pyecraft has annoyed Formalyn so much he is not particularly nice with his descriptions of Pyecraft’s size.  On the other hand this might be a pro because it could lead to a discussion on how weight is viewed in our society and is it fair for Formalyn to say the things he does about a desperate man.  Wouldn’t it be interesting if the story was written from Pyecraft’s point of view?

How I use this in my class

In my classes I usually have my students explain the scientific misconception in the story, and then they have a choice.  They could: 1) Write an original story that explores a scientific fact or misconception 2) Create a comic that explores a scientific fact or misconception 3) Outline an original project that explores a scientific concept or misconception through visual arts, song etc.

To be honest I never really considered that Pyecraft might be a desperate man until this year when a convergence of coincidences shined some light on the plight of the overweight.  My view of him turned from pathetic to sympathetic, so I think next year I might add an option to rewrite the story from Pyecraft’s point of view.

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Jennifer teaches science in a public school in Pennsylvania. She lives there with her husband and two dogs.

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