Answers to Do You Know of NovDec 2013

1. The Voyager 1 and 2 spacecraft went past Jupiter, Saturn, Uranus and Neptune. Has no one ever though of visiting Pluto?
Answer: NASA's "New Horizons" space craft is heading for a meeting scheduled for July 2015 with the dwarf planet Pluto (discovered in 1930), its moons Charon (discovered in 1978), Hydra and Nix (discovered in 2005), the yet-unnamed P4 (discovered in 2011) and P5 (discovered in 2012).

2. Which animals sweat?

Answer: Most animals do, though not in the same way as humans, who sweat to keep
cool. Dogs, for instance, pant for that purpose.
Humans have two sorts of sweat gland and two sorts of sweat. The first type with which we are most familiar are in our skin all over the body and produce watery droplets. The droplets evaporate from the surface and cool the skin so they are important in regulating our body temperature.
This sort of sweat gland and sweating however is very uncommon in animals. Very few animals use sweating to keep their bodies cool. A second type of gland forms sweat by breaking off bits of cell rather than secreting a droplet.
The product is much more granular and fatty. In humans, this is the smelly sort of sweat. Most animals do have this sort of sweat gland, but they are fairly few and far between and mostly concentrated around the face and mouth. They seem to be important for keeping the skin soft and flexible, and the smell acts as territorial marker or signal fear and anxiety. 
Dogs and cats incidentally have a large number of these sweat glands on their footpads. They are probably there to keep the pads which are just very thick skin, supple, but may also help with grip in the same way that we lick our fingers to make them slightly moist when counting bank notes or turning pages.
Horses sweat abundantly. There is a type of protein related to albumin in their sweat which often causes it to froth. 
Human beings can sweat out as much as 10 to 14 litres per day!

3. Was Einstein's brain different to mine?
Answer: When the great scientist Albert Einstein died, his brain was removed and it was photographed before being dissected and the majority of the slides are now stored at the National Museum of Health and Medicine in Washington DC, USA. The main researcher that did the dissection fixed his brain with formalin and cut it into 240 really small blocks and sent them around the world to different researchers to study.
According to researchers' description of the structure of Einstein???s cortex, the outer bit of the brain did suggest that the cerebral cortex folding pattern was unusual in some areas, those that might be related to cognition and mathematical reasoning. It also had a slightly large area of one side of the hand control region which was thought to be linked to his violin playing. 
One study suggested that Einstein???s brain may have had more glial cells. These are a kind of supporting cells that help secrete factors (like cholesterol for example) that help nerve cells to connect with each other. 
But scientists have cautioned about the value of these studies, pointing out the fact that everyone???s brain is slightly different. Einstein surely had certain fantastic abilities and he was a good violin player. But was he fantastic at everything? No. You are probably much better than he was at some things than he was, say in writing poetry. So, there's a part of your brain that perhaps we should fix and send around the world when you die!

4. How much damage can a rupee coin dropped from some height do?
Answer: Suppose that it is actually dropped from the Burg Khalifa in Dubai, currently the tallest building in the world, 830 metres high. And it hits your head! Ouch! How badly would you be hurt?
We don't live in Dubai, but we can try out an experiment from any tall building nearby. Try this from a 4-storey building, approximately 12 metres tall. Go to the top, drop the coin and measure the time it takes to fall using an accurate stopwatch. 
After a short drop, objects start to be opposed by air resistance, so they reach what is called terminal velocity, a steady speed that cannot be increased no matter how far they fall. Because we know how fast gravity makes things accelerate, we can work out how fast a coin would fall without air resistance and then see if it reaches terminal velocity. 
For our experiment, it should take about 1.6 seconds to reach the bottom. If it takes longer than that then we can assume that we must have reached terminal velocity. 
You see that it actually takes about 2 seconds to hit the ground, which means that the coin is very definitely reaching terminal velocity, even after a distance of 12 meters. So, dropping it from a higher tower, it would not be going really much faster than the speed that you have seen. We are really talking of perhaps 5 to 10 meters per second which is no more than 35 or 50 KM an hour. It is not terribly dangerous. You can easily throw the coin that hard at somebody sitting across. Even if you threw a bundle of coins at them, it might hurt but that person is not going to die. 
It would be a different matter if you spin the penny like a spinning wheel. Then it would slice through the air with far less air resistance, move much faster, and could hit you edge on, so it would be much more dangerous.
No, it's not a good idea to try, so resist the temptation to drop things from heights! 

5. What chemical leaks from batteries?
Answer: Suppose that you have left the battery cells in say a torch, for more than a year. When you open it again, you see that something has leaked. There is a white powder around the contacts of the batteries and also on the contacts of the bulb. What is this powder? Is it harmful to touch? What would be the best way to clean this powder away? Will the powder be harmful to new batteries that you insert?
What is actually happening here is the electrolyte from the battery is leaking out. In batteries, there is a reaction going on between two metals and there is an electrolyte in the middle that allows charge to be transferred between the two sides of the battery. Usually in normal alkali batteries it is potassium hydroxide. Eventually though, your batteries do keep reacting even if you have not connected them up. They react very slowly, but they do leech a little bit and there could be side reactions, and eventually, they can just pop open. At that point, the electrolyte comes out. 
Potassium hydroxide is not very nice. It is alkaline, and caustic. However, it then reacts with carbon dioxide in the atmosphere. So actually, what you see as white crystals is potassium carbonate (called potash). It is not dangerous, you can use a weak acid (like lemon juice) to try and neutralise it as you are washing it off. 
There is no permanent damage and new batteries should not be affected. One worry is that if left long in electronic goods, the leak can creep into circuits and start degrading them.

6. When ice falls as hail it is hard, whereas snow is soft. Why?
Answer: Both the ice of a hailstone and the ice in snow flakes are the crystalline form of solid water. However, they are formed in different conditions and through different processes leading to differences in their internal structure and hence different physical properties.
Snow is precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes. Snow forms mainly when water vapor turns directly to ice without going through the liquid stage, a process called sublimation. Since it is composed of small rough particles it is a granular material. It has an open and therefore soft structure, unless packed by external pressure. 
Hail is also a form of precipitation, but composed of spears or irregular lumps of ice. It occurs when supercooled water droplets (remaining in a liquid state despite being below the freezing point, 0 degrees C) in a storm cloud aggregates around some solid object, such as a dust particle or an already - forming hailstone. The water then freezes around the object. 
Depending on the wind patterns within the cloud, the hailstone may continue to circulate for some time, increasing in size. Eventually, the hailstone falls to the ground, when the updraft is no longer strong enough to support its weight. 
The hailstones are 5mm in size and are often much larger. And because a hailstone is a sizable mass of solid frozen water, it is hard. Snow particles form when water condense into micro-crystals of ice, less than 1 thousandth of a millimetre in size. The connectivity of tiny ice blocks is rather fragile in the snow flakes, making snow flakes feathery and soft.
Sources: The Naked Scientists, Scientific American, NASA, Wikipedia