History has shown that the Earth's magnetic poles have switched over past history.  How would a modern switch affect such technology as electrical generation, electric motors, and all things magnetic including Compasses and GPS.

Probably is a blind shot, but I would like to ask if somebody has calculated the impact in global warming of the direct heat. I am thinking for example in the human population (almost 7 billion with a constant  average temperature of 36.5 º C). And not only that, but the average temperature of all the cattle in the world kept by humans, (billions of animals that otherwise wouldn´t exist). Also we could think in the heat from fires (both wildfires and the small ones) and the heat that escapes from our homes, vehicules or industries.

i think currently the largest are around 151,687 gross tonnes.

Why would this perfectly good tank car be sacrificed to make a point about proper procedures?

In this video, you see it collapse on camera.

Will anyone venture an estimate of the forces involved?

http://www.youtube.com/watch?v=E_hci9vrvfw

Being the heaviest organism on the planet (ignoring anything that photosynthesises or any ridiculously big fungi), baring in mind it lives in water, a blue whale is a huge lump of a mammal and probably has the capacity to reach some speed if given a chance and could probably cause great distress to krill populations if it where to waste more energy painting on go faster stripes. What's the fastest a blue whale has ever been recorded? It has probably never felt the need to outrun a predator or to leap on unsuspecting krill, and isn't really built for speed and has never seen the point in chasing after...anything at all...except krill...and maybe to out compete males if it itself is a male. Theoretically how fast could a blue whale swim if it let it's metaphorical hair down?

Being the heaviest living organism on the planet (that doesn't photosynthesise or isn't a ridiculously big fungi) , baring in mind that it lives in water, what's the fastest a Blue whale has been recorded swimming? being a huge lump of a mammal, it has probably never felt the need to out run anything or take on random spurts of speed to leap on krill, nor is it built to race...much at all...except krill..and maybe other blue whales for a mate. but theoretically how fast could a Blue Whale be if it let it's metaphorical hair down? Thomas Frost, Suffolk, UK

If you sink an object and then let go then it accelerates upwards. What if I sank something a very long way (say a mile or so)?

I've read in New Scientist about the potential of using supercavitation to travel very fast through water.

So what’s to stop me attaching a lightweight projectile onto a big rock with a piece of string which will detach at a certain depth, dropping it off a boat and firing something into space?

I garden under the flight path to Bristol airport and listen to the radio. I,ve tried to use a wind up radio but every time a plane flies over the battery drains instantly and i need to wind it up again. Considering a plane comes over every 5 minutes it's impossible to use one. Why does this happen?

Tsunamis move fast, and tow-in surfers use various vehicles to catch large waves. A friend has a son who wants to ride a 100-foot wave. Is this possible? How big of a wave could an unassisted surfer catch?