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Posts posted by ARS

  1. So... Today, I revisit my old collection of games for nostalgia. Among those are Call of Duty Modern Warfare 2 (2009 one, not the 2020 remaster). While playing it, something strikes my curiosity: In 2 consecutive mission (Contingency and Second Sun), a nuclear missile was launched from submarine base in Russia towards US east coast before detonating at high altitude to create EMP effect that cripples Russian troops on US soil. The one that interest me is the missile itself. Judging from what I've seen in-game:

    1. Contingency started at August 14th, 2016 at 11:22:34. Assuming a normal playthrough, player would likely reached the submarine base within 10 minutes of playing, adding the obligatory defend objective at the end, at most this will take around 15 minutes, so let's assume the missile is launched at 11:37:34

    2. Second Sun takes place at August 14th, 2016 at 18:57:20, (roughly 7 hours 19 minutes and 46 seconds after the missile has launched, let's assume it's 7 hours and 20 minutes). From the viewpoint of sat 1, he's likely in-orbit above southern portion of US east coast. At this point, shortly after the mission start, the missile can be seen coasting over horizon. After a short chatter with mission control, the missile detonates and knock the power across US soil and also destroyed the ISS

    Judging from the submarine model in the sub base, it's either Yankee or Delta-class, since other Russian SLBM-capable submarine class are too different than what's seen in-game. There is a developer oversight however, regarding the missile flight path from the submarine at Petropavlosk, Russia to very high altitudes above Washington, D.C. The missile was depicted in mission briefing as flying away from Petropavlosk to northwest (the long path, with a distance of around 26,000 Km), where the correct angle for shortest flight path is northeast (the short path, with a distance around 8600 Km). The missile was later depicted from Sat1's view as approaching Washington D.C. from northeast (long path), where the correct approach angle is from northwest (short path). Now, assuming the technology level of 2016's ballistic missiles (the year the game takes place), does a distance of 26,000 Km from Petropavlosk to Washington DC is possible to cross in 7 hours and 20 minutes with parabolic trajectory? Is it way too fast or way too slow?

  2. Is there any reason why firearms magazine has particular shape? (I'm talking specifically about the regular 30-rounds magazines, not drums) There are magazines that's curved forward (M4 or AK), straight (FAL or G3) and swept backward (Vector). Is there any reason for the shape or it's just for aesthetic purpose? Considering all of them do the same thing: Push the bullets inside upwards

  3. When long-duration space mission using probes are conducted (which can take years, such as Dawn mission). After setting the flight and orbit parameter of the probes' autopilot (when to do burn, how long the burn is conducted, craft orientation, hibernation mode, etc.), when the probes are on escape trajectory from earth's gravity well, does the mission control keep tracking the probe everyday for years until it reached the point for flight maneuver adjustment (such as when entering another celestial body's gravity well for gravity assist, maneuvering for rendezvous, etc.), or just do like what most KSP players did with ion engine burn? Estimate time for the next maneuver (which can take years) and go grab a lunch downstairs (or wait for years), come back when the time comes to do the maneuver?

  4. Why the design for reentry vehicle is always smooth-curved (like the underside of space shuttle or the design of Apollo/ Soyuz capsule). What if the reentry capsule/ vehicle design itself is viable for reentry but with highly angular design? (aka, same design, but all smooth and curved part is turned into blocky angular), compare Apollo/ Soyuz capsule with WH40k space marine drop pods

  5. Does the solar reflector satellite in the Bond film "Die Another Day" actually makes sense in context of real-life application? It's said in the movie that the satellite is meant to focus solar energy on a designated area and provide year-round sunshine for crop development. Does this makes sense in real life concept of application? (even without the laser module, someone would came up with the idea to weaponize it). I mean, crop development is actually going normally today, with current day and night cycle. It's not like the crop needs sunlight exposure for 24/7 just for increased productivity, unless the daytime sunlight exposure is so dimly lit like post-nuclear winter that it necessitates direct sunlight reflection from space

  6. 2 hours ago, JoeSchmuckatelli said:

    If Earth had a higher oxygen percentage in its atmosphere - would paper burn at a temp higher than F451? 

    In the fire triangle, there are 3 things needed to form a combustion: oxygen, heat and fuel. Modifying any of these parameter will change how things burn. In case of oxygen, if you're increasing the oxygen percentage of the atmosphere, it speeds up the process of combustion. Higher oxygen percentage on the atmosphere will create an even faster burning process. However, like in the fire triangle, things have to be balanced: Too much oxygen with too little fuel means the paper will be burned to ash almost instantly before the fire becomes self-extinguishing because there's nothing left to burn. Too much fuel with too little oxygen means the fire will also self-extinguishing before the paper fully burned because there's not enough oxygen to sustain the process. By default, oxygen itself is not flammable, but it does support and required for the combustion process, adding more just accelerate it or even makes things catch fire at lower temperature (that doesn't stop early alchemists and researchers calling it "Fire air"). If you want paper to burn at a temp higher than F451, the parameter you need to change in the triangle is the fuel (aka the paper itself), not the oxygen content (some materials do becomes significantly more combustible (more reactive) than usual in high oxygen environment, look no further than Apollo 1 fire that killed 3 astronauts)

  7. So... I found a stuff on Youtube that compressed a compilation of songs (around 60 minutes of songs) into 2 seconds-video. The idea is if you played the song at super ultra-slow speed, you could listen the entire song. So I'm wondering, if audio files can be compressed into shorter length (for example, to send a secret message in a particular segment of a song), is there a limit of message length that can be compressed into 1-second audio before it starts to be unreadable as a message (aka, just garbled noise no matter how slow it's played, like the pixels on "zoom and enhance" situation)?

  8. Does the heat propagation (from hot object to cold object) affected by the temperature difference between the 2 objects? Does the greater the difference means the colder object more "receptive" towards the heat from hotter object? For example:

    There's a hot iron rod with a temperature of 100 ºC. The temperature is uniform on the surface of this iron rod. Now we attach 3 iron rods at once (all touching the hot iron rod at the same time), but each of them has different temperature: rod A is at 70 ºC, rod B is at 35 ºC and rod C is at 0 ºC

    Does the rod C more "receptive" with heat propagation because of  it's much larger temperature difference with the hot iron rod compared with the other 2? (in other words, rod C is prioritized more for heat flow than rod A and B)

  9. Does this situation possible considering how light reflects off a reflective surface?

    2 Snipers are hunting each other. They are elite soldiers expert in camouflage. At one point, while both are under camouflage, and facing each other (they're not aware they are staring at each other), the sun is positioned in such a way that the sunlight glints from the scope's lens of both of them (basically they see the scope glint of each other, not just only one of them)

    Also, since lasers can reflect off reflective surface, is it possible for sufficiently powerful laser to not reflect off reflective surface at all simply by burning through it from the sheer amount of heat at the moment of contact? Basically a laser that melts through the mirror it's supposed to reflect off

  10. Weird, I often left my mining outpost unattended and never had any problems like that. Maybe you need more radiators? Forgot to activate it? Or maybe it's just a glitch. I don't know, but for my 3 years playing KSP I never had such a problem. Though my mining outpost is also beyond the timewarp range since the main base is very far away, so maybe timewarping while it's still in range might cause it

  11. I wish that the kerbals have specialized EVA suit based on their job occupation, complete with specialized abilities and features. I've made a concept for it long time ago

    Pilot: can use maneuver nodes while in EVA, jetpack has extra fuel and has more powerful thrusters strong enough to be used as actual jetpack on atmospheric condition. Suits has much more G and heat tolerance. Maneuverability and controls for EVA movement is more responsive. Parachute has more air control. More options while piloting craft such as "leveling aircraft"

    Engineer: can use mining auger to perform small scale mining, with onboard micro ISRU providing refueling capabilities for EVA jetpack for self or other kerbals. Has onboard solar panels on EVA suit that can be used to passively recharge nearby batteries or drone cores. Has a small onboard antenna to transmit science report from nearby Kerbal or craft (it's much weaker than even the weakest antenna, but better than nothing). Has brighter and wider flashlight illumination area

    Scientist: can carry handheld experiments and other scientific instrument items on EVA backpack's slot, allowing the science experiments to be conducted with boots on the ground (different from the one slapped on the craft of plopped on the ground). Automatically refresh the non-repeatable experiments and has more options for "no tool science" than pilot or engineer while on the ground other than "take surface sample" and "sitrep". Can store several science report of the same type (but not unlimited like experiment storage box). Reduced scientific efficiency loss when collecting same science report over and over again

  12. I prefer they take their time to finish and polish KSP2, even of it means delaying the release date. Glitch and bugs at release is inevitable, no game is perfect, but there's a major difference between glitch/ bugs that occurs during normal plays and those that happens during abnormal play. Take KSP for example, if your SSTO suddenly stages it's part in flight even though it has no staging at all, then yeah, that's a very serious one that isn't supposed to happen in normal play. On the other hand, the one that happens during the abnormal play is the one that happens during action that the player does not expected to do in normal play, like how Danny2462 found all of his game breaking shenanigans because you're not supposed to grab Kerbal and pull them apart with 2 asteroid grabbing claws. Though this also makes me say that, in the eyes of Kerbal: "there are no glitches/bugs in KSP, only krakens"

  13. This turns out to be much longer than what I expected. Ok to clarify some stuff, I have a task in my metallurgical department. Let's just say we're measuring the atomic distance of a cupronickel alloy sample (apologize for the confusion about compound and alloy) in material's lab (each group may or may not get the same sample). The goal is to find the distance between atoms in the crystalline structure of the sample, first the distance between the atoms of same types (Cu with Cu, Ni with Ni) and the second is the distance between the atoms of different type (Cu with Ni). Things go as planned before suddenly, in the middle of operation, the test machine broke (can't blame it, it's kinda old anyway). We asked the teacher for the solution for this and basically it boils down to the "if the actual test can't be performed, then use the mathematical calculations to find it out"

    Now we could calculate the atomic distance of individual types when it's separated, but for the atomic distance for alloys, things get complicated. The ratio of cupronickel in question is 3:1, the distance from each Ni atoms should be uniform, same case with Cu. The main question is, how to calculate the distance between Ni and the nearest Cu atom inside the cupronickel alloy, and the distance between Ni atoms with each other in cupronickel allow with a ratio of 3:1 (assuming Ni atoms distributed evenly), it doesn't matter if it's exact value or approximate value (if we change the ratio, then the distance between Cu and Ni should be different too, right?)

  14. [Moderator's note:  This topic was originally split off from For Questions That Don't Merit Their Own Thread, since the ensuing discussion turned out to be a lengthy one.]

    Is it possible to calculate the distance between molecules on a metal compound purely by mathematical calculation as long as we know the ratio of the metals used, density and molar mass of each metal as well as the resulting shape of the crystal matrix of the compound? Assuming that the metal constituent is evenly distributed in ideal condition

  15. Considering their appearance, behaviour and their stupidity (or suicidal overconfidence) tendencies, then yeah, I consider them cute, especially their expression of joy (or terror) when their aircraft are barrel rolling towards the cliffside at 1200 km/h with one wing missing (I still try to not them get killed though. Planes are easy to replace, skilled personnel are not)

  16. The An-225 Mriya has twintail design to mitigate the lack of airflow when Buran is loaded on top the fuselage by moving the rudders on the sides. If for example, on aircraft with large propellers on wings placed directly on the way of rear twintail with short fuselage length, (think V-22 Osprey design) does the fast-moving airflow from behind the propellers hitting on twintail rudders actually improves rudder performance compared with regular airflow without propellers in front of the twintails?

  17. 4 hours ago, K^2 said:

    Temperature isn't related to energy, but rather.......

    Thanks for the answer. It really helps me to define the changes of energy between cold and hot temperature.  I got the idea for the question when I stumbled upon a sentence:

    "...coldness isn't energy, but rather lack of it (from the point of view of our environment's parameters)..."

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