Recently Answered Questions

Updated May 25, 2010!

• How many veins are in your body?
  Veins are blood vessels that carry blood towards the heart. Most veins carry blood that has been deoxygenated in various parts of the body and is now destined to be re-oxygenated in the lungs before being sent away from the heart in arteries. It is not known precisely how many veins there are in the human body, though it is thought that if you took all of the arteries, veins and capillaries from an adult and laid them end to end they would form a line up to 100,000 miles long!
• What is the cotton wool? What is the best material to muffle the sound?
  Cotton wool as we know it here in Ireland is generally made from raw cotton which is combed, bleached white, sterilised and then formed into the balls and other shapes that we all have in our homes. The best material to muffle sound is a more complex question. In one sense distance and space is a good material to muffle sound. For example, you cannot here a car or jet engine if it is a long distance away. However, we can’t always move away from the source of a noise so several materials can be used to absorb sounds. In order to muffle sound we need to do two things: 1) absorb it and stop it from echoing and reflecting around the space it is in and 2) form a barrier that stops noise from travelling through things like walls so that it can be heard outside in the next room. There are a range of materials that can be used to achieve these two tasks. One of the best materials for absorbing sound is Acoustic Mineral Wool or Sheep wool insulation which is very dense wool that disrupts the passage of sound waves to such an extent that their strength or noise is greatly reduced. This material can be placed between walls, floors and ceilings.
• What is reflection?
  Reflection is what happens when a wave of light bounces off a surface. When light hits a shiny surface, like your mirror at home, nearly all of it gets bounced back from the mirror. As a result you can see a reflection of yourself that is the same size as you, but is back to front. Reflection like this from a mirror or a very flat surface like a lake is known as specular reflection. When light hits a more uneven surface a ‘diffuse’ reflection can occur. Think of the difference between matte and glossy paint. The shinier glossy paint gives a specular reflection where you can almost see yourself, while the matt paint gives a diffuse reflection that reflects the light without reflecting an image. Light is not the only energy that reflects though. Sound waves can also be reflected in echoes. The reflection of sound is also used in submarine sonar systems.
• Why do i have red hair?
  Red hair is the rarest natural hair colour. Globally, only 1 or 2% of people have red hair, but in Scotland and Ireland it's much more common. Up to 10% of the population is made up of red heads. Red hair looks red because of the pigment pheomelanin, and associated with the MC1R recessive gene. Your mum and dad both passed on this gene to you, even if one or both of them don’t have red hair themselves. Be careful in the summer, because people with red hair tend to be very fair-skinned, and can easily suffer sunburn. Red hair is lovely, but red skin not so much!
• How fast does lava run down a volcano?
  There are lots of different types of lavas, with different chemical compositions and behaviours, but the main thing you have to worry about if you're running down the mountain with a river of lava chasing after you is the viscosity! Highly viscous lava is like stew. It tends to flow slowly, and contain interesting lumps. Lava with low viscosity, on the other hand, is like soup. Low viscosity lava is a lot more scary because it's much more runny and fast flowing. Usually lava moves slowly enough for people to escape, but with a steep enough slope, and a low viscosity, lava has been known to reach speeds of up to 100 km/h.
• Why is earth surrounded by other planets?
  The earth, and all the other planets in the solar system formed just by chance, from the odds and ends left over from the creation of the sun. The sun started to form 4.6 billion years ago from a giant molecular cloud. Most of the material gathered in the middle. A little bit was left over, spinning around the sun as it got hotter and hotter. These left-overs eventually became planets, and they still spin around the sun today.
• Why are bubbles in water spherical? Why aren't they triangular or cubed?
  Bubbles are round because they are what is known as ‘minimal surface structures.’ What this means is that the always contain whatever is inside them within the smallest possible surface area. The shape with the least surface area for any given volume is…you guessed it, a sphere. However, while bubbles on their own are always spherical, bubbles surrounded by other bubbles can form different shapes. Try and blow several bubbles that stick together and you may see that some of them are square or hexagonal in shape. These shapes are not occupying the least possible space though, so once you start bursting the surrounding bubbles you’ll see that they will revert to their round shape once they are standing alone again.
• What’s the difference between Prokaryotic and eukaryotic cells?
  All living things are constructed of cells, and cells are split into two major classifications: prokaryotic and eukaryotes. Prokaryotic cells are the simplest living cells and have been in existence for billions of years. In fact for a long time prokaryotic cells were the only form of life on earth. The cells are characterised by the absence of a separate membrane bound nucleus or organelles, and by DNA that is loosely organised rather than arranged in chromosomes. If you want to see prokaryotes at work try making some yoghurt. It is created when bacteria (which is prokaryotic) comes into contact with milk. About 2 billion years ago prokaryotic cells evolved into more complex cells called eukaryotes. The defining feature of these cells is the presence of a membrane bound nucleus in which genetic material is carried. Most eukaryotic cells also contain other membrane-bound organelles such as mitochondria, chloroplasts and Golgi apparatus. Almost all large organisms are eukaryotes including animals, plants, fungi and other groups referred to as protista. While prokaryotic cells reproduce by binary fission – where they duplicate their genetic material and essentially split in two, eukaryotic cells can reproduce in one of several ways including sexual reproduction and mitosis.