697: Tensile vs. Shear Strength
|Tensile vs. Shear Strength
Title text: Although really, the damage was done when the party planners took the hole punch to the elevator ribbon to hang up the sign.
This comic is set in the future, where engineers have successfully constructed a space elevator, until Black Hat decides to cut the cable linking the ground and space using pruning shears. This demonstrates how tensile and shear strength are not the same. Tensile strength represents how hard you can pull on something without it breaking. Shear strength represents how hard you can try to cut it without it breaking. Many materials have great tensile strength but low shear strength (such as dental floss — try to break it by just pulling on two ends), including whatever this space elevator is made of. The material clearly has extremely high tensile strength because it can hold the elevator in place, with one end on the ground and one in space, but it can be cut with a simple pair of pruning shears. This also highlights the fact that "shear strength" and "shears" are etymologically related.
A space elevator is a proposed construction that would make space travel easier. It consists of a long string attached to the Earth (near equator) on one end and a counterweight (beyond the geostationary orbit) on the other end, kept taut and in one place by the gravity and centrifugal forces. This would make it possible to carry spacecraft into the orbit by simple mechanical means, as opposed to requiring the use of rockets as is the case nowadays, saving a lot of energy and resources.
The phrase "a modern Babel" refers to the biblical story of the Tower of Babel (later referenced in 2421: Tower of Babel), in which humans endeavor to build a tower reaching heaven. Their arrogance angers God and prompts him to sabotage the project. A space elevator can be seen as a modern equivalent of a tower to heaven. Additionally, the expression "a modern Babel" may be used figuratively to describe huge projects (especially buildings or human-made structures) that fail because they are too ambitious.
The title text makes the point that even before Black Hat cut the space elevator's ribbon-like cable in two, it was ruined by the holes in it for the banner. The holes would reduce the surface area of the cross section of the ribbon, reducing its ability to keep the elevator attached to the ground. The flag and holes would also potentially make it impossible for the elevator to travel up the ribbon, making the entire elevator useless.
- [A space elevator occupies the height of the frame, consisting of a base, a cable extending out into space, and an elevator unit with standard elevator features such as sliding doors and up/down buttons. A banner flutters in the breeze attached to the cable going up above the elevator. There is text on the banner. Text appear in four lines split across the elevator cable itself, the rhyming portions of the text is on the right side of the cable. Five individuals stand at the base of the elevator. To the left are Megan, a Cueball-like guy with his arms raised, and Ponytail, who is holding a bottle of champagne/sparkling wine which is bubbling out down the neck of the bottle. To the right is Black Hat, who cuts the cable with a pruning shear like it was part of the ceremony as a ribbon cutting. Finally further right is Cueball who sees what Black Hat is doing. He is very alarmed holding a hand to his mouth while holding the other out towards Black Hat.]
- Banner: Space Elevator
- Banner: Grand opening
After countless engineers spend trillions over fifty years, a modern babel disappears because some fuck brought pruning shears.
- Pruning shears: Snip
- Cueball: !!
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