Check out all the questions that Molly has previously answered.
In this section you'll find explanations for the science behind everyday things such as how popcorn pops and why shopping bags rustle!
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Does counting really ever stop!!
No, you could count forever and never run out of numbers. This is known as ‘infinity’ and in maths, there is a symbol for infinity that looks like an 8 on its side. ∞. Infinity doesn’t just apply to numbers though. Imagine walking around the world until you reached the end? Well, you could go forever because the planet is round and has no ‘end point.’ Similarly, it would be impossible to count all the stars in the sky because they just go on, for ever. Even if we can’t see them because they are so far away, we know that there are stars, planets and whole solar systems that go on...to infinity.
Did NASA invent Velcro?
Velcro, also known as ‘hook and loop fastener’ is a fabric that is made up of two layers – a ‘hook’ side which is covered with tiny hooks, and a ‘loop’ side which is covered with tiny fuzzy loops. When these two sides are pressed together thousands of hooks catch into the loops and the sides are held together.
But of course you know this, because you probably use Velcro every day to fasten your shoes or keep your coat snugly closed!
The material was invented by a Swiss engineer called George de Mestral, who noticed one day that his dog’s fur was covered in plant seeds after a hunting trip to the Alps. When he looked closely he saw that the seeds stuck themselves to the dog by using tiny hooks to catch into the fur. After years of research de Mestral introduced his invention to the world, but it was when NASA used it to help astronauts quickly take on and off their bulky space suits that Velcro really became popular. This is why people believe to this day that it was NASA rather than de Mestral who invented this ingenious material.
Why do we need to wear sunscreen?
Everybody knows that you have to be careful that you don’t spend too much time in the sun without covering your skin or wearing protective lotion.
The sun’s light contains invisible rays called UV or Ultraviolet rays that cannot be seen but can be harmful to our skin if we don’t protect ourselves. There are two types of UV rays, UVA and UVB. UVA rays cause serious damage while UVB rays are responsible for causing us to tan, and get sunburn. When sunlight hits our unprotected skin, the UV rays damage some of the cells on the surface of our skin. This damage can be seen as a tan or sunburn. Sun block lotion is designed to minimise the harm that the sun’s rays can cause by either absorbing the UV light and releasing it as heat, or by deflecting the UV light away from us. You can tell the strength of sun block or sunscreen products by looking at the SPF or Sun Protection Factor number on the bottle. The SPF tells you the amount of time you could spend in the midday sun without getting burnt. For example, if you had no lotion on and your skin went red after 10 minutes in the sun, wearing a sun block with an SPF of 15 would allow you to stay in the sun for up to 15 times longer, or 150 minutes. As they say in Australia, where the sun can burn you very quickly, the best advice when you are going out in the sun is to Slip-Slop-Slap – “Slip on a shirt, slop on sunscreen, and slap on a hat.”
Why does the water in our toilet move when it’s windy out?
I’ve noticed this too...when it’s a really windy day sometimes the water in the toilet seems to be moving as if the whole house is shaking. A little investigation reveals that the answer is a combination of science and plumbing! In most houses there is an air vent connected to the plumbing for the toilets and taps that leads up towards the roof of the house. The vent lets any yucky gases or smells escape, and it stops the pipes from gurgling when you are doing something like emptying the bath. On a windy day though, as gusts of wind pass over the entrance to the vent they temporarily lower the air pressure in the pipe, creating a small suction effect in the plumbing system that causes the water in the toilet to move about. In science this is known as the ‘Bernoulli effect.’ If you would like to learn more take a look at the Aeroplanes activity in the Activities section of this site.
Why can you eat raw fish but not raw chicken?
Raw fish, known as sushi ,is very popular in Japan and increasingly popular around the whole world. So why is it safe to eat uncooked fish but not uncooked chicken? Well, chickens run the risk of being contaminated with bacteria that can cause food poisoning such as E. coli or Salmonella. This is why we are told to wash our hands after handling raw meat and to cook meat like chicken and pork really well. While bacteria like salmonella can also be found in fish it is less common. However, the fish that we eat raw still has to be very carefully prepared. For example, the fish is often processed very quickly after it is caught and frozen to -20 degrees celcius for 15 hours or more to kill any parasites that may be present and prevent any bacteria from spreading from the guts to the flesh. So, while sushi is safe to eat you still need to be careful with raw fish.
Is food a great thing?
Yes, yes it is. Food is essential to human life. Every living thing needs energy to survive as it enables movement, growth and reproduction. Humans get our energy from the food that we eat. As we gobble down that last delicious mouthful of food our body is already busy digesting it, breaking down the food so that the nutrients it contains can be used to give our body and mind the energy it needs. Nutrients are the nourishing parts of food like vitamins and minerals. Different types of food contain nutrients like carbohydrates, protein and fibre that we need to eat in balanced amounts so that we have all the energy we need to be able to learn in school, run around at breaktime and have healthy brains and bodies. Of course, it is important to eat the right type of foods and make sure that you get lots of fresh fruit and veg in your diet as this really will help you to grow big and strong.
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.
On a cold morning, if you touch a coin it will feel cold and when you touch a pencil it doesn't. Why is that so?
I think the key word here is that the coin 'feels' colder than the pencil.
Your sense of how hot or cold an object feels depends on the direction of heat flow between you and it. When heat flows from it to you, it will feel warm to touch, and when the opposite is the case it will feel cold.
A key factor effecting how hot or cold things feel is conductivity – or the ability of a material to transfer heat efficiently.
Both the coin and the pencil are conducting heat away from your body when you touch them, except that the metal conducts heat better and so it feels colder. The wood does not conduct the heat away from your body as well and so it does not feel as cold.
The metal coin and wooden pencil can be described as Conductors and Insulators. Think about other materials that might be called insulators – maybe your clothes, an animal’s fur or the material that lines your attic.
Which is heavier, water or milk?
Milk is heavier than water! Why? Because milk has more material in it than plain water. Milk contains sugar, salts, fatty matter and other materials such as minerals. All of these items make milk slightly heavier than normal water.
When we talk about the weight of milk versus water we are touching on the topic of density. Density can be thought of as how much something of a set volume weighs. For example if you had a litre of tap water, sea water and milk you would find that even though you have the same amount of each liquid, they all have slightly different weights because they all have different densities.
Who invented the wheel?
It’s hard to imagine life without the wheel isn’t it? Many of the machines that we use everyday need wheels to make them work. And wheels are not just used for cars and buses! They are also important in watches, computer disk drives and sewing machines. So how was the wheel invented?
Because it happened so long ago we will probably never know who the first person was who figured out how useful the circular shape of the wheel could be. While it is estimated that wheels were in use up to 8000 years BC, the earliest records of wheels in use come from around 3500 BC in Mesopotamia – which is in modern day Iraq. In this case wheels were being used not for transport by potters to make bowls and jugs. The first use of wheels for transportation was probably on chariots in the same area around 3200 BC. Wheels appeared in Egypt around 2000BC and in Europe around 1400 BC.
It is thought that the invention of the wheel was probably a gradual discovery rather than a sudden realisation. For example, people moved heavy loads by dragging them on top of lots of logs and rolling them along the ground. As the load moved the logs would have to be continually placed in front of it. Eventually someone may have thought that instead of using lots of logs a single one could be used with the help of an axle. At this point we would begin to see a wheel that we recognise as being similar to the ones in use today.
How to prevent egg from breaking?
Eggs shells are just thick enough to keep the outside world out while the animal inside is developing, and they are just thin enough to allow that animal to force its way out when the time comes to hatch and enter the world.
As a result, egg shells are actually quite strong if they are exposed to an even amount of pressure, for example when a bird sits on an egg to incubate it. However, eggs are weak when pressure is applied to them directly. That’s why they break easy when dropped or cracked off the edge of a flying pan. Egg cartons are used to protect eggs from small knocks, but to really protect an egg from breaking in a fall you need to surround it with something that will absorb the force that occurs when it hits the ground and suddenly stops moving. There are lots of things you could try, maybe tissue paper, or bubble wrap. Not all eggs are so weak though. The ostrich lays the largest and heaviest eggs in the world, weighing around 1.7 kgs. The eggs are so strong that a man can stand on them, and you would need tools to crack one open!
Why does coke fizz up like a volcano when a mint is put into it?
By now lots of us have seen a bottle of Coke turn into a fountain as soon as some mints are dropped into it.
But why does this happen?
Well, the drink is fizzy because it has carbon dioxide (CO2) dissolved within it. When the mint enters the liquid, tiny holes in its surface allows the CO2 to rapidly form bubbles – a process called nucleation. The liquid becomes a fountain because the CO2 goes from being dissolved in the liquid to being a gas very quickly, but as it is trapped within the bottle the increased pressure means that it shoots out the top, bringing the coke with it.
What are rulers made of besides plastic?
The ruler you use in school can be made from a variety of materials, from plastic to wood or metal. The important thing is that the ruler gives you a standard way of measuring in inches as well as centimetres and millimetres.
Did you know that people have been using different ways of measuring distance for thousands of years? For example, the Egyptians and Babylonians used a measure called a cubit which was defined as the length of a man’s arm from the elbow to the end of his middle finger! Do you think that was accurate? If you stand beside your friend and compare your arms I’ll bet you’ll find that they are not quite the same length.
Over the centuries a range of different measurement units have been used but it is only in recent times that it has been agreed internationally to make sure that these measurements, such as yards, fathoms, feet and meters are the same all around the world.
Are all shadows black in colour?
The simple answer is no. Although most shadows appear dark in colour, generally shadows are not completely black. The colour of a shadow depends on how it is formed. For instance on a sunny day, shadows may appear very black in contrast to the glare of the bright sunlight. And you can even get coloured shadows! For example, certain types of windows such as stained glass church windows cast coloured shadows. Shadows can be quite useful in our day to day lives. For instance, the shadow or shade of a tree is a great place to rest on a hot summer's day.
Are mobile phones dangerous?
Millions of people own a mobile phone these days, but ever since they have been around people have asked whether or not they are safe. And although some studies have suggested that mobile phones may be hazardous to health, there is no definite evidence to indicate that we should stop using them. However, the problem is that mobile phones are still a relatively new technology so we do not yet know what long-term effects they may have on out health. It’s true that mobile phones give off a low level radiation. However, many other household appliances also do. The bottom line is that more research is needed. In the meantime, potential risks may be reduced by using hands-free kits and keeping mobile phone calls short.
What is time?
Hmm, that’s a tough one! In fact for centuries, scientists, philosophers, religious leaders and probably just about everybody else has at some stage pondered the same question. And as far as I can see, there is no simple answer to this question yet. If you look in the dictionary, time is usually defined as being part of a measuring system, in other words it’s an arrangement we use to sequence and timetable events, to measure the durations of events and the period of time between them. But time also has a more mystical meaning. Time is passing non-stop. We cannot study it with a microscope or experiment with it so therefore we cannot say what exactly happens when time passes. All we know is that time will ultimately affect us all as we grow, learn, live and age.
How many litres of oil does it take to make plastic bags in Ireland per week?
Hmmm, tough question! Not sure I can give you an exact answer to that one. What I can tell you is that it’s estimated that for every ton of plastic bags that are reused or recycled, the energy saved is the equivalent of 11 barrels of oil. That’s a pretty shocking fact when you consider that the 1.26 billion plastic bags used in Ireland each year weigh in at just about 14,000 tons.
How does a thermos flask keep hot drinks hot and cold drinks cold?
The answer to this question has a lot to do with heat movement. Imagine for example, you leave a glass of cold lemonade at room temperature. After a while, the lemonade will have heated up to approximately room temperature. Likewise with you left a hot cup of tea sit on the table, it’ll eventually cool down to yep you’ve guessed it, room temperature. A thermos flask basically stops this process of liquids either heating up or cooling down. It does this because of the special way in which it’s made. A thermos flask basically contains one bottle inside another bottle. The air is removed from the space between these two bottles. This produces a vacuum effect. Vacuums do not allow easy movement of heat and therefore helps to keep the liquid within the thermos at a constant temperature.
Where else do scientists do experiments, aside from a laboratory?
There is no end to the various locations where scientists carry out experiments. Depending on what’s being investigated, scientists may travel to exotic and far-flung destinations. For instance, botanists and zoologists often travel deep into the jungle or to the bottom of the ocean to study plant and animal life in their natural surroundings. Some environmental scientists have even faced great danger in order to record and study natural phenomena such as tsunamis, volcanoes, earthquakes, avalanches and hurricanes. Some scientific experiments have even been conducted in space onboard the international space station. So in other words, not even the sky’s the limit!
How does a swimming pool stay clean when so many people swim in it a day?
Ever heard of a useful little chemical called chlorine? Well, if not, chlorine is basically the answer to your question. Chlorine is added to swimming pools to keep them free of nasty bacteria that could potentially make the otherwise happy swimmers quite ill. Unfortunately, too much chlorine in swimming pools can smell quite unpleasant and cause skin irritation in those with sensitive skin. That’s why other ways of keeping swimming pools bug-free are being investigated. And as for the bigger bugs, leaves, sand and other yucky stuff that can wind up in a swimming pool, these are collected and removed regularly as the water in most swimming pools is continuously pumped through a filter.
What is your favourite Science Experiment?
Hmm, that’s a tough one. There are so many…but I think this has to ‘bee’ one my favourites. The experiment was performed by Karl Ritter von Frisch (an Austrian scientist) to study the ‘Waggle Dance of the Honeybee’. As funny as this sounds the waggle dance is actually an amazing method of communication between bees. The dance is performed by a worker bee upon return to the hive. By using particular dance movements, the worker bee ‘tells’ other bees where to find pollen or nectar. While dancing, the bee’s body, especially its abdomen, wags vigorously from side to side. Sure sounds like bees know just how to have fun at work! To study the dance, von Frisch used glass-walled hives and paint-marked worker bees. He trained the worker bees to find food placed a certain distances from the hive. When the bees returned from gathering food from those areas, von Frisch recorded its dance movements and in this way deciphered of the ‘Waggle Dance of the Honeybee’.
What is the best science thing you've done?
There have been many memorable experiments over the years but one of my favourites is the ‘Make a Rocket’ experiment found on the Activity section of this website. I like this experiment because of its simplicity. It just uses a chemical reaction - a "fizz"-producing tablet and water - to produce thrust. This launches the film canister forward. Although it seems very simple, the rockets that launch spacecraft and satellites work on exactly the same principle. Of course, these cost hundreds of millions of Euro!
What's the difference between the oil that my parents put in the car and the oil they use for cooking the dinner?
Believe it or not, vegetable oil (the one used for cooking chips) and motor oil (the one used in car engines) are quite similar! They both share the usual physical characteristics of all oils, i.e., they do not mix with water and they are liquid at room temperature. However, chemically, they differ quite a bit. Vegetable oil belongs to the 'triglyceride' sub-family of oils, whereas motor oil belongs to the 'hydrocarbon' sub-family. Triglyceride oils are generally made up of carbon, hydrogen and oxygen atoms, whereas hydrocarbons are made up of just carbon and hydrogen atoms. Generally, motor oils are made from petroleum which in turn is derived from crude oil which is found naturally in the ground. On the other hand, vegetable oils are derived from plants and seeds.
Why does popcorn pop?
Everybody loves popcorn and everyone is familiar with its popping sound in a microwave or saucepan. Basically popcorn pops when it is heated above a temperature of approximately 205 degrees Celsius. This causes the hard outer shell of the popcorn kernel to explode and pop. This happens when moisture inside the kernel is heated. When the moisture inside reaches a very high temperature, it turns to a vapour or gas. The pressure from the vapour builds up inside the kernel eventually causing the shell to explode. That's how you end up with those familiar pops and a very tasty snack!
How do you make a light work?
A light bulb is basically a small metal wire that is glowing with heat and contained within an airtight glass casing. The metal is called tungsten and remains solid even at very high temperatures (and in the absence of air; that's why a light bulb has to be airtight).
When you turn on a light switch, electricity flows into and through the wire of the light bulb, causing it to heat up. This causes the wire to glow and give off light. The wire heats up because, when electricity passes through it, some of the electrical force is absorbed by the metal and given off as heat. When a light bulb "burns out", it is because the wire has slowly 'vaporized' or worn away or over time.
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