Timeline for Would trams be workable on a low-gravity world?
Current License: CC BY-SA 3.0
11 events
| when toggle format | what | by | license | comment | |
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| Mar 16, 2018 at 0:58 | comment | added | John Dvorak | @Rekesoft not exactly. You have doubled the contact pressure but also halved the contact area. The total force (both the normal force and friction) remains the same. Your modified carriage won't move faster, just wear out faster. | |
| Mar 15, 2018 at 13:59 | comment | added | Jammin4CO | Why not just have assisted start and stop! Like a rollercoaster launch. The force needed to maintain speed would be much less. | |
| Mar 15, 2018 at 12:46 | comment | added | Rekesoft | Instead of loading up the trains to make them heavier you can just reduce the number of wheels per wagon. If you reduce your 8 wheels wagons to just 4 wheels, you have just doubled the friction between wheel and rail for the same wagon weight. | |
| Mar 15, 2018 at 5:56 | comment | added | Tim B II | @immibis thanks, that's exactly what I thought. Smaller engine because climbing is easier and because maintaining velocity is easier because of virtually no air pressure. Even slower acceleration on the flats isn't so much an issue because it would actually help with grip (friction) by not applying too much force at once. Couple that with cog-rails, and you've got a very efficient transport mechanism. Thanks again. | |
| Mar 15, 2018 at 5:47 | comment | added | Stack Exchange Supports Israel | @TimBII That's correct, the energy needed to move horizontally is the same as on Earth. The energy needed to go uphill is less. However note that you'd intuitively expect to not need as big of an engine, and you'd be right, because once you're up to speed, the engine is only countering energy loss from air resistance and friction, and there is a lot less air to resist. | |
| Mar 15, 2018 at 5:41 | comment | added | Tim B II | Thanks for that @immibis but out of interest; am I right in assuming that the lateral energy required to move mass around on Mars is the same because Force = Mass * Acceleration, but that the vertical energy required to lift it a set amount (say up a mountain range) is less because the gravitational force is less? I'm thinking that we need a trigonometric equation for kinematics in 3 dimensions that factors in both mass and weight on planetary surfaces other than Earth. | |
| Mar 15, 2018 at 5:30 | comment | added | Stack Exchange Supports Israel | By the way, theoretically, if you loading up the train with more cargo then the extra friction exactly cancels out the extra force needed to move the extra cargo, so you still get the same amount of acceleration in the end. (But it does mean you need less trains to move the same amount of stuff) | |
| Mar 15, 2018 at 5:29 | comment | added | Stack Exchange Supports Israel | I like your cog-rail idea. | |
| Mar 15, 2018 at 0:57 | comment | added | Tim B II | Hi @Sean, the lower gravity would compensate IF you haven't loaded more mass onto the train to increase weight, and IF you don't have to apply a higher acceleration (power output) to forward motion than the wheels can handle in friction. One of the reasons Earth trains find it hard to climb is that the steel on steel works well on flats because of the train's weight putting pressure on the connection, but uphill the wheel wants to roll back, meaning that the incline itself is putting pressure on the friction at point of connection as well. | |
| Mar 14, 2018 at 23:33 | comment | added | Vikki | Actually, some rapid transit systems do use rubber tyres, which I noticed just now. Regarding weaker engines making it even harder to climb inclines, wouldn't the lower gravity compensate for that? | |
| Mar 14, 2018 at 23:26 | history | answered | Tim B II | CC BY-SA 3.0 |