TheJeeronian
TheJeeronian t1_j1rb99t wrote
Reply to ELI5: Cars move without pressing the gas pedal. When you put it into drive why does the car automatically start rolling if your not pressing the gas? by xd_Hashtags53
In automatic transmissions, there is a torque converter. This is like two fans, one connected to the engine and one to the start of the transmission. This allows the car to sit still while the engine moves.
As long as the engine is moving, the fan is blowing oil at the other fan, and so it's pushing the car forward. When you step on the gas the fan blows harder and so the force forward is stronger.
TheJeeronian t1_iy9ove6 wrote
Reply to ELI5: Would the sound of a spaceship leaving Earth slowly disappear to the people inside of it? by 4thesuns
Almost all of the sound of the rocket comes from inside the rocket. Its main path to the passengers is through the rocket. This path is not interrupted when you remove the air.
TheJeeronian t1_iy94pui wrote
Reply to comment by MotsPassant in ELI5: how does gasoline work like it’s just a liquid how does it power cars?? by [deleted]
Gasoline does not refer to a gas, ironically
TheJeeronian t1_iy75fsv wrote
Sure. None that currently exist, but sure.
It'd have to be an insanely high-end printer, probably using crazy-expensive feedstock, but yeah sure. It'd hardly destroy any industry, though.
3dp is usually one of the worst ways to make something. It is super convenient for making one or two, but for any product it is garbage. Anything a modern 3d printer can make in four hours with a lot of care and tweaking, an injection moulding machine can make in four seconds and repeat ten thousand times before it needs maintenance.
TheJeeronian t1_iy6swrf wrote
When gas burns in air, it becomes a gas and gets hot. When a gas gets hot it expands. When a gas expands, it can push things.
So we trap it in a tube, burn it, and when the gas in the tub expands it pushes on a 'cap'. When the cap moves it pushes the wheels forward. Do this a thousand times a minute and you've got a decent amount of energy for a car.
TheJeeronian t1_iy5uz6w wrote
Reply to comment by Any-Growth8158 in ELI5 what is dy/dx? by EarlaSallow
It's a pretty fun thought experiment to make up a value and pretend that this value is d(sign(x))/dx at 0, then try to run through some normal calculus with this new constant.
TheJeeronian t1_ixs7fvp wrote
Reply to comment by xYoSoYx in ELI5: why does tire pressure decrease in the cold? by xYoSoYx
It shouldn't. As I mentioned, outside air pressure is pretty much fixed. There's a bit of variation but almost none. None big enough to be significant compared to tire pressure.
Humidity within the tire matters when it's inflated. A tire inflated with hot and humid air will lose a lot of pressure as it cools, but a tire inflated with cold and dry air will not gain nearly as much pressure as it heats up. This is because the amount of air and water in the tire is fixed, but the water may expand or contract quite a bit with temperature. The outside humidity once the tire is sealed makes no difference.
TheJeeronian t1_ixrwfzy wrote
At 32 psi tire pressure (46 absolute) inside and 14 absolute outside, a decrease of 10% pressure would leave you with 41.4 absolute inside vs 12.6 outside. The relative pressure has dropped by, you guessed it, 10%. Now you're at a 28.8psi.
However, there are other factors at play, too. The atmosphere's pressure depends on both its temperature and volume, and its volume is not limited by any container, so a hotter atmosphere will expand but the pressure can stay the same.
In fact, the pressure does stay the same, because it is the weight of the air in the atmosphere that gives it pressure, whereas in a tire it is the tire walls stretching and keeping the air in that gives it pressure.
This all compounded by the nonlinear PV-T behavior of tire gas, especially water, which sees a huge pressure/volume drop as you approach 0 degrees c. Our atmosphere also has water in it, though, so without my first two points this wouldn't matter.
TheJeeronian t1_iuja849 wrote
Yes and no. It's relatively easy to avoid the blast, if you have the money to spend making it happen. Bunkers are an obvious choice. How long you stay down there depends a lot on what was dropped where. One bomb a mile away? You can leave in a day. Global nuclear apocalypse? It'll be a while.
TheJeeronian t1_iuhxav4 wrote
Reply to comment by Terravash in ELI5: Newton's third law by AppropriateFeeling44
Our walls here are usually drywall with supporting wooden studs. The flexure is invisible but easily measured
TheJeeronian t1_j1w1uj9 wrote
Reply to ELI5: If time is the fourth dimension, then what force is pushing us through it? by quacduck
It is not a spacial dimension. Our movement through time works very differently from movement through space.
However, movement through space does not require a force. An object in motion stays in motion. If time did behave like a spacial dimension, then the only time any force would be pushing us through it is when we came in contact with something moving at a different speed.