Activity for dsrâ€
Type | On... | Excerpt | Status | Date |
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A: Determining a Practical Bridge Design for a Wide River and Heavy Traffic Neopanamax beam is just under 52m, with a height of just under 60m. Let's give it about 50% margins on each side, and that give you 100m between bridge supports. A suspension bridge with a 100m span would not appear on a list of notably long bridges in our world. Suddenly this is not looking like ... (more) |
— | 10 months ago |
Answer | — |
A: Could there be a way for a solar system to be very precise, so that the lunar calendar and solar calendar align? Something you may not have thought of: the Earth-Luna system has the barycenter inside the Earth's radius. Fairly deep inside, in fact -- about 25% of the way down from the surface. Your system as described is less binary-like than our own. Either the moon is smaller than Luna, or farther away, or... (more) |
— | 11 months ago |
Answer | — |
A: Price's Law Sanity Check For the sake of a fictional story, you should be thoroughly aware that the author is playing as a god. The laws are what you want them to be, and what you say happens is what happens. I am not aware of any experiments to determine the validity of Price's hypothesis. If you want it to be true in yo... (more) |
— | over 1 year ago |
Answer | — |
A: Could a high-pressure, low oxygen atmosphere reduce fire risk while still being breathable? Your intuition is correct. Let's suppose that at STP, a human needs to breathe 1L of O2 in 200 minutes. That's 1.43g of gaseous oxygen. If the pressure is raised to 5 bar, a human still needs 1.43g of O2 -- but it will only take up 0.2L of volume, and the other neutral gas mass will have to increase ... (more) |
— | about 2 years ago |
Answer | — |
A: Human elytra flying off a cliff An average human masses 60Kg. The largest bird ever to fly, Argentavis, massed about that much. https://en.wikipedia.org/wiki/Argentavis So it seems reasonable that flying creatures the same weight as a human need to be reasonably close to Argentavis's size. Argentavis' wingspan was about 6m, a... (more) |
— | over 2 years ago |
Answer | — |
A: Could a habitable planet lit by the cosmic microwave background plausibly exist? A back of the envelope calculation suggests that you need a velocity relative to the CMBR of more than 0.9c. (1mm microwaves blue-shifted to 570nm light typical of yellow dwarves) This is a problem for several reasons: - there is no known mechanism to create a planet with that velocity relative... (more) |
— | almost 3 years ago |