Know4KnowledgeSake
Know4KnowledgeSake t1_iugf7eg wrote
Reply to ELI5: if Earth rotates so fast, why does it always look still from outer space? by ShesOver9k
A lot of really good answers already. One thing I didn't see mentioned is you may also see videos from geostationary orbits which would make it look like the earth isn't rotating at all (though if you pay attention you'll notice space is "rotating" behind it). Could be messing with your perception depending on the context.
Know4KnowledgeSake t1_iugfres wrote
Reply to ELI5: How exactly do we get some much power from engine now, than we did 40, 50, 60 years ago? by Micromashington
More like 40-50 years, and a lot of this also has to do with how easy/cheap things are too manufacture. But in two words: Volumetric Efficiency. Engines are just giant air pumps. You cram more air in each cylinder per cycle, and you've effectively driven more air through the pump. Air moving = energy (because air has mass and thermal properties).
The higher the cylinder pressure, the more fuel & air you've crammed into the cylinder, the more power you make per ignition.
The biggest factor in our ability to manufacture cheap, high-pressure engines is: Metallurgy. Metals have made leaps and bounds in the past 30 years, and where once you needed expensive iron closed-deck blocks to eke out big cylinder pressure, you can now more easily do with carefully-designed, precision-machined aluminum blocks that weigh less, have better thermal properties, more homogeneous crystalline structure (stiffer), and thus can manage higher cylinder pressures (more boost).