927 reputation
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bio website ericmenze.com
location Minneapolis, MN
age 30
visits member for 2 years, 11 months
seen 12 hours ago

I'm a Computer (Web) Programmer/Analyst based in Anchorage, AK and Minneapolis, MN. I use (among other things) ASP.NET, C# and SQL Server.

I build things. Bicycles, computers, websites, guitars, cars, motorcycles, sound sytems... lots of things.


Jan
20
asked Would cosmological redshift be present in the following situation?
Jan
17
comment What would happen to matter if it was squeezed indefinitely?
Why would isothermal compression be a valid interpretation of the question? Performing an infinite amount of work on the substance has the potential to raise the temperature an infinite amount, and indeed without some magical heat sink, the temperature would rise and the substance would take a more or less positive slope through the phase diagram (though it may not be linear). Thus with enough force compressing (and heating) the substance, a vast majority of substances will transition through a gas and a plasma on their way to electron degeneracy, and ultimately a black hole.
Jan
14
comment Rocket Propulsion, delta V, acceleration and time. How do they relate?
Delta V goes up. Let's examine the same rocket, 4,000kg empty, 8,000kg fully fueled, and now let's strap on another 8,000kg bolt-on fuel tank that is magically 100% burnable fuel. You now have $ \Delta V = v_e * ln ( \frac {m_0} {m_1} ) = 4.0 km/s * ln ( \frac {16,000 kg} { 4,000 kg } ) = 4.0 km/s * ln (4) = 4.0 km/s * 1.386 = 5.545 km/s = 5,545 m/s $ In this example the fuel was 3/4 the total mass, where in the previous example it was 1/2, and that extra 1/4 gives us just twice the $ \Delta V $ (when you think about it, 3/4 could be used as two maneuvers of 1/2 the craft mass in fuel each).
Jan
14
awarded  Good Answer
Jan
14
revised What would happen to matter if it was squeezed indefinitely?
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Jan
13
comment Rocket Propulsion, delta V, acceleration and time. How do they relate?
A good read to get a better understanding of this is xkcd's rocket golf: what-if.xkcd.com/85 . What's important to note is that the only way to change your velocity (accelerate) is to throw/push/explode/golf something the opposite way. The speed at which it leaves you is $I_{sp}$, quantity of mass you hit/move/throw/burn per second is your flow rate - in my example above, 4,000kg of fuel was used in 10s, so 400kg/s was the burn rate.
Jan
13
comment Rocket Propulsion, delta V, acceleration and time. How do they relate?
I caveat the above comment to say that there are likely counterexamples to all of those, methods by which solid rockets can be throttled, bi-propellant setups that cannot be, etc. Estes model rocket engines are examples of full thrust 'til empty.
Jan
13
comment Rocket Propulsion, delta V, acceleration and time. How do they relate?
Well I doubt 'throttle' would be the appropriate name for them (they don't 'have' throttles), but yes they have mechanisms by which they can throttle (verb) their thrust. For example, liquid bi-propellant uses pumps to mix fuel with liquid oxygen, and by varying the flow rate they regulate thrust - the SSME is engaged at low thrust during solid rocket boosting for example. In hybrid rockets, they can regulate gas flow rates, whereas some solid propellant rockets (like boosters) have no method of regulating thrust or reignition - they're full blast until out of fuel.
Jan
13
awarded  Mortarboard
Jan
13
revised What would happen to matter if it was squeezed indefinitely?
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Jan
13
comment What would happen to matter if it was squeezed indefinitely?
Good catch! I interpreted that as 'infinitely strong' in the spirit of what I thought was being asked, but you are correct here. It would all get sucked into the black hole of the piston first!
Jan
13
awarded  Nice Answer
Jan
13
revised Rocket Propulsion, delta V, acceleration and time. How do they relate?
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Jan
13
revised Rocket Propulsion, delta V, acceleration and time. How do they relate?
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Jan
13
answered Rocket Propulsion, delta V, acceleration and time. How do they relate?
Jan
13
awarded  Critic
Jan
13
revised As a car turns around a circle, why does the force of static friction point towards the center of the circle
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Jan
13
revised What would happen to matter if it was squeezed indefinitely?
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Jan
13
revised What would happen to matter if it was squeezed indefinitely?
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Jan
13
answered What would happen to matter if it was squeezed indefinitely?