TED-Ed_ How much land does it take to power the world_ 04:27 TED-Ed_ The world's biggest battery looks nothing like a battery 04:56 TED-Ed_ Why good ideas get trapped in the valley of death -- and how to rescue t 04:50 Thomas L. Dawson_ What causes dandruff, and how do...
While solar sails have been designed before (NASA's had a solar sail program back in the 1970s), materials available until the last decade or so were much too heavy to design a practical solar sailing vehicle. Besides being lightweight, the material must be highly reflective and able to to...
While solar sails have been designed before (NASA's had a solar sail program back in the 1970s), materials available until the last decade or so were much too heavy to design a practical solar sailing vehicle. Besides being lightweight, the material must be highly reflective and able to to...
Some might find it ironic that an organization like NASA, who studies our atmosphere, is Ok with rockets polluting it so much. Or isn’t it weird that Elon Musk, the same person who is pushing sustainable energy with Tesla, also has a rocket company that runs on fossil fuels? And let’...
A car's top speed is generally a good indication of how powerful an engine it has, but assuming everyone stays within the speed limit, maximum speeds are just numbers on paper—little or no use to anyone.Acceleration is much more interesting than speed and more useful if you need to get...
Even though the action and reaction of the rocket motor during burn is equal, the mass of the fire, gas, and smoke being propelled by the rocket engine is much smaller or less than the overall mass of the rocket being sent in the opposite direction. As a result, even though the force...
Because much of New Orleans lies below sea level, the city is at risk from flooding. Emergency management officials must begin evacuations (疏散) well before a storm strikes. But evacuation costs money: Businesses close, tourists leave, and citizens take precautionary measures. The mayor of New...
at a mandatory shipping cost of $10.75. Paying that much for shipping bothered me when I can get to and from the Capitol for $6 and change via Metro, less if I use Capital Bikeshare on the way there. Fortunately, the legislative branch of the U.S. has two houses, so I checked the...
And then he starts to fall back in, and he falls, he falls along the same parabolic or ballistic trajectory that he would if he were just a rock. If someone threw a rock up there, it'd be the same kind of parabola. He's on a ballistic trajectory and can't do much about it. ...
Space suits cannot use normal air -- 78 percent nitrogen, 21 percent oxygen and 1 percent other gases -- because the low pressure would cause dangerously low oxygen concentrations in the lungs and blood, much like climbing Mt. Everest does. So, most space suits provide a pure oxygen atmosphe...