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In the word ‘radioactive’, the word ‘radio’ stands for ‘radiation’. If a substance is radioactive, it means that it is actively radiating alpha (helium nuclei) and beta particles (electron) and high-frequency electromagnetic waves of the spectrum (gamma rays) away. Radioactivity has nothing to do with radio waves.

There is a limit. And this limit depends on the height of the river. So as long as you have a height you can build dams in a cascade fashion and run a hydroelectric powerplant. The limit ends where the height reaches the sea level. You will be better off building one plant at a very steep area of the river than building consecutive installments as the river water starts losing kinetic energy and height down the stream.

Substances change phase when there is a change in its energy. The usual process we are used to at home is water boils to form water vapor and freezes to form ice. This gives the idea that water is an intermediary liquid state between gas and solid. This is right! But not all the times.

Under certain atmospheric conditions, a solid like ice can change its phase to a gaseous phase and vice versa without going through the intermediary liquid phase. Ice changing from solid phase to vapor is known as sublimation. Similarly, vapor changing to solid ice is known as deposition.

This is the phase diagram for water:

When the atmospheric condition meet the right conditions where the temperature is below 0 and the pressure is lower than 10 kPa, the solid form of water (ice) will undergo sublimation to form gas (water vapor). You could see this atop peaks like Everest.

Some GIF avatars should have been carried over after the patch.

A body in the Earth’s atmosphere is usually heated by the Sun, the IR radiation reflected from the surface, and the gas molecules around it. As the altitude increases, temperature increases as you have mentioned. But the density decreases with altitude as well. So when you’d shoot up yourself to the thermosphere, you will be in a very less dense area. There will be not enough gas molecules surrounding you to conduct heat. This is why the thermosphere won’t heat you up! In addition to this, your body will also radiate away the heat inside you. Due to lack of conduction, you will eventually start feeling cold in the thermosphere.

Hi Fernando,

The number of naturally occurring elements is usually prone to debate. According to stability, atoms are stable only up to the 92nd element – Uranium. Your teacher is correct when she says there are 92 elements that occur naturally on Earth. But when you carefully analyze each element, the elements Technetium and Promethium don’t have stable isotopes, and by its properties are extremely unstable with smaller half lives. So your text book might have discarded these two elements.

Looks great! Love the simple layout. Why don’t you use the same for Geekswipe? I still love the existing layout, but Blip is way more simpler.

As you mentioned, practically no real world mirrors are 100% reflective. In theory, it is still complicated. Even if you have a 100% reflective mirror and a parallel light, gravity will affect the trapped photons and there will be a phase change.

Periodic Table of Spectra

I think the guardian article is self-explanatory. A rubber ball that has a significant velocity and thereby a great change in momentum will absolutely be dangerous for the brain. If you dig enough you will find heaps of pending cases involving ex NFL players claiming for concussion damages. This also gives enough data about the long term injuries. I wonder why those researchers left them out in their studies. If you are interested, read this survey results.

• Birds/cats/dogs/ hear some weird sounds before the secondary wave.
• They freak out just the way any normal life forms would do.
• After the events, humans like to believe that there is a sophisticated mechanism to it.

I hardly can live without internet even for a minute. I wish I could go offline some days, but I end up watching cat videos just like every geek at the workplace. My wife on the other hand, she totally has an internet free life. No mail, no social network, no nothing! She uses my old Blackberry for calls. Her real life addiction is books. Thanks to her, my kids are off the devices too. Maybe I’m half blessed here.

My all time favorite! Music of the night… :)