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39 views

What is a realistic launch speed of a grappling hook gun? [closed]

In The Dark Knight, at the end of the movie Batman throws the Joker off of a building and then shoots his grapple hook gun to catch him. Is 68m/s a reasonable speed for a grapple gun to shoot?
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53 views

Is it possible to reach lower temperatures than the Boyle temperature in de van der Waals equation?

We know that for a real gas we can write a virial expansion in powers of $p$: $$pV=Nk_{B}T+B(T)p+\cdots$$ It results that the van der Waals equation: ...
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221 views

Modeling galactic colonization

I found a really cool sounding order-of-magnitude modeling question but am a bit at a loss on how to approach this: The Milky Way contains 100 billion stars and has a radius of 250,000 light ...