Title text:
"How does the spring not run out almost immediately?" "We pull it back REALLY far."
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3244/
This reminds me of the advanced spring powered devices in Syberia (the adventure game). I wonder if it is even remotely feasible to store that much power in springs, probably not.