The Science of Fireworks

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We all know the history of Bonfire Night, but do you know the science?

The Explosion

All fireworks are essentially a combustion reaction, like fire, that produces light and heat.

Fireworks tend to have a long fuse that burns slowly so you have time to light the fuse and run away before the big bang! The fuse first reaches a compartment containing gunpowder, it ignites this causing the firework to launch into the night. There is a delayed fuse to ignite the next explosion, this heats the “stars”.

The stars in a firework are individual compartments containing a different composition of chemicals, depending on the desired colour and effect of the firework. The stars may even be arranged inside the shell of the firework so that they burst in a certain formation to form a shape.

The Colours

Firework displays always use a range of striking colours, the variety of colours comes from the use of different chemicals. Elements such as barium, copper and lithium burn with a coloured flame and are chosen for use in fireworks due to the bright colours they produce.

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The Sound

When the chemicals inside the firework’s shell are heated they convert from a solid to a gas. The gas takes up more space than there is available inside the shell so it bursts out creating a loud BANG.

Crackling noises come from fireworks which contain lead. When lead oxide is heated and vapourised, the vapour atoms produce crackling noises.

The whistling sound that you hear when the fireworks shoot up in the air, comes from the firework tube itself, not the chemicals. When the tube is partly empty, it will vibrate the air passing through it, causing a whistle.

How can you write your name with a sparkler?

I’m sure you’ve all held a lit sparkler at some point and twirled it around in the air to see a trail of light lingering in the air for a few seconds. The truth is the light isn’t really still there but your eyes play a trick on your brain to make you think that it is. Image resultOur eyes don’t react as quickly as you might think when our view changes, they usually keep the old view around for a fraction of a second. This is known as visual persistence and it’s what allows us to view a series of still images as movement. The effect is increased in the case of the sparklers due to the very bright light emitted form the sparks contrasting against the dark background. This makes the light appear to last longer.

 

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#TryThisTuesday: Honeycomb

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Honeycomb or Cinder Toffee not only makes a great Bonfire Night snack, it’s also a fun and quick science experiment! Here’s our simple recipe for the honeycomb reaction:
1. Grease a baking tray with butter and set aside.
2. Mix 100g sugar with 2.5 tablespoons of golden syrup in a pan. Mix the two well before you heat the pan.


3. Gently heat the pan, try not to stir the mixture at this point just let it gently begin to melt.
4. Once you can see the sugar start to melt you can push the sugar around to ensure in melts evenly and doesn’t burn.
5. When all the sugar has melted turn up the heat so the sugar begins to boil and forms an amber coloured caramel
6. Turn off the heat and add one teaspoon of bicarbonate of soda, beat the mixture quickly as it begins to bubble up to incorporated all the bicarb then tip onto the greased baking tray.


7. Leave to set for 30-60 minutes then enjoy!

The Science

The heat causes the bicarbonate of soda (NaHCO3) to break down and release the gas, carbon dioxide (CO2). The gas gets trapped within the sugar, this results in the bubbles in your honeycomb.

honeycomb

The Chemistry of Being Scared

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Happy Halloween! We all like being scared sometimes, whether it’s scary movies or a rollercoaster, but why do we get scared?

We feel fear when we see or hear something that makes us anticipate harm. If you are walking through a haunted house this Halloween and a skeleton jumps out at you, the skeleton is a stimulus that triggers a signal in your brain.

The hypothalamus is part of your brain that activates the ‘fight or flight’ response. When you are scared molecules of glutamate (a neurotransmitter) travel to the hypothalamus. This then triggers the autonomic nervous system, a response that you can’t control.

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Nerves from the brain carry impulses to glands which produce adrenaline, released into the blood. Adrenaline causes our heart rate and blood pressure to increase making us ready to run away quickly.

When we get scared we also get goosebumps. This is a trait that evolved in our hairier ancestors. When our hair stands up on end it makes us look bigger and more threatening to whoever is scaring us. This is seen in other animals too, such as cats.

However, we aren’t scared forever. Eventually our body realises that there is nothing to be worried about.  Sensory data of what we have seen and heard is sent to the hippocampus in the brain which can store and retrieve conscious memories. It gives context to what we have seen and asks questions such as have I seen this before and what happened last time?

If a skeleton jumps out, we will realise that it isn’t real and is probably just someone dressed up! The hippocampus will determine that there is no danger and sends a message to the hypothalamus. Adrenaline production stops and our heart rate goes back to normal.

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We have evolved to feel fear to allow us to survive. People and animals who feared the right things survived and passed on their genes. This makes sure we don’t do stupid things like picking up poisonous snakes or walking off buildings.

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Black History Month: 6 Influential Black Scientists

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To honour Black History Month, we’ve taken a look at some notable black scientists and what they have achieved in their scientific fields.

1. Benjamin Banneker (1731-1806)

The son of a former slave, Benjamin was born in Maryland, USA. In 1753, he produced the first working clock in America, it struck every hour on the hour. Benjamin was also a keen astronomer and worked on calculating lunar and solar eclipses.

2. Ernest Everett Just (1883-1941)

Raised by his mother in South Carolina, USA, Ernest grew up to become an influential biologist. He argued that cells should be studied as a whole under normal conditions, rather than breaking them up and subjecting them to unnatural lab conditions.

3. Percy Lavon Julian (1899-1975)

Percy was born in Alabama and went on to study at Harvard University and the University of Vienna in Austria. Percy was an American chemist who focused on researching the chemical synthesis of medicinal drugs from plants. His work paved the way for the mass production of contraceptive pills and he also worked on large scale synthesis of human hormones, such as testosterone.

 

4. Charles Richard Drew (1904-1950)

Charles was the first African American to earn a Doctor of Medical Science degree. During World War II, Charles worked on a revolutionary project called Blood for Britain, he created trucks that stored refrigerated blood that could be transported to soldiers in need. He also set up blood donation centers and ensured all blood was tested and handled correctly. Charles’ work led to the American Red Cross Blood Bank and undoubtedly saved thousands of lives.

5. Maggie Aderin-Pocock (1968)


Born to Nigerian parents, Maggie grew up in London with dyslexia and the ambition of becoming an astronaut. Despite discouraging teachers, she went on to earn a BSc in Physics and a doctorate in Mechanical Engineering from Imperial College London. Maggie worked on a project to probe the centre of stars billions of miles away. Maggie is passionate about inspiring young children to pursue careers in science and has presented various BBC science documentaries.

 

6. Mae Jemison (1956)

Mae was the first African American woman to travel in space. She is a keen advocate of science education with a particularly interest in getting more minority students to go into science. Through her own company, the Jemison Group, Mae runs a science camp for children aged 12-16.

 

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#TryThisTuesday: Slime!

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slime

With Halloween coming up, what better time to make some of your very own slime?

It’s super easy and quick to make – you just need to mix water and cornflour! Start with a little bit of both, if it seems too runny you can add more cornflour and if it becomes a solid then add more water.

You can also add food colouring and glitter if you want to add some sparkle to your slime.

The slime should become a consistency that appears to be a liquid but if you hit it or try to stir it quickly it becomes a solid – so which is it?

Liquid or Solid?

Slime isn’t actually a solid or a liquid – it is a non-Newtonian fluid, this is a fluid that changes its properties when a stress or force is applied.

The slime we’ve made is a particular non-Newtonian fluid called oobleck (yes it’s a funny sounding word – that’s because it is derived from a Dr. Seuss book). The particles of cornflour don’t dissolve in the water, they become suspended in the water and repel each other. Mechanical stress, such as stirring quickly provides energy that overwhelms the repulsive forces, causing the particles of cornflour to temporarily stick together. When the stress is removed, the repulsion returns and the slime becomes liquidy again.

More Non-Newtonian Fluids

1. Custard behaves just like oobleck, in fact if you filled an entire swimming pool with custard, you would be able to walk across it!

2. Ketchup is almost the opposite of oobleck – it become thinner and runnier under impact, that’s why it helps to bang the end of a ketchup bottle when you’re struggling the get some out.

3. Whipping cream acts differently when under a constant and prolonged stress, such as whipping. If you whip cream for long enough it will appear to go from liquid to solid as it becomes whipped cream.

4. Honey similarly needs prolonged stress to change it’s properties. When you stir honey, it will become more like a liquid than a solid.

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World Egg Day: Eggsellent Experiments

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Happy world egg day! Here are some cracking eggsperiment that you can at home on this very important day:

Egg in a Bottle

For this experiment you will need a hard boiled egg, an empty plastic bottle, a scrap of paper and a lighter.

Light the paper and drop it into the bottle. After a second place the egg on top of the bottle and observe the results.

The lit paper heats up the air in the bottle, causing it to expand slightly and for some air to escape. The egg creates a seal so more air cannot enter. As the air cools inside the bottle it decreases the pressure and forces the egg into the bottle.

Floating Egg

All you need to try this one is an egg, a glass, water and salt.

Fill you glass half full with tap water and carefully place the egg inside. It should sink. Add some salt until the egg floats. The salt increases the density of the water, when you add enough the egg becomes less dense than the water so floats to the top.

Next dribble spoonfuls of tap water down the side of the glass until it is full. The egg should appear to float in the middle of the glass, it is actually floating on top of the salt water with a layer of fresh water above it.

Hard boiled Spin

Lay a hard boiled egg flat on its side and spin it. Put your finger on it to stop and then let go, nothing remarkably happens there. Try the same with a raw egg and when you let go it will start spinning again on its own accord.

This is all due to momentum. When you spin the eggs you spin their insides too. In the hard boiled egg, the insides are fixed to the shell so it behaves as you would expect. In the raw egg the insides continue to spin after you’ve stopped the shell. When you let go, the momentum of the spinning yolk carries the shell and the whole egg starts spinning again.

 

#TryThisTuesday: Making Plastic from Milk and Vinegar

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plastic

Yes – you really can make plastic from just milk and vinegar!

First of all just measure out 120ml of milk (it can be any type, we used semi-skimmed). Either heat your milk in your microwave or in a pan on the hob. It needs to get to around 50 degrees C so 1 or 2 minutes in the microwave should do it.

Next add 2 tablespoons of white distilled vinegar to the hot milk and stir – you should see clumps start to form.

Sieve the mixture to remove the excess liquid. Remove even more liquid with a paper towel or piece of kitchen roll.

You should be left with a clump of plastic which you can mould and shape as you please. It should begin to set in an hour.

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The Science

Plastics are polymers meaning they are made up of long chains of repeated molecules (called monomers). The monomer that we have used is called casein and is found in the milk. When the milk is heated the casein molecules unfold. Adding the vinegar causes them to reorganise into a long chain polymer – making it a plastic.

It might look quite different to the plastics you’re used to today but up until the end of World War II in 1945, casein plastics were commonly found.

9 Scientific Mistakes in Disney and Pixar

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Sorry to crush your dreams but we have inspected some of our favourite Disney films and some things just don’t sit right in our scientific minds. Here are nine examples of what would really happen, according to science. But remember anything is possible in the world of Disney…

1. Finding Nemo

All clown fish are born male. Each group of clown fish has one female, the biggest fish. When the female dies, the biggest male fish will become female, this is know as being a sequential hermaphrodite.  When Nemo’s mother was killed by the barracuda, Marlin would have become female, leaving Nemo as the dominant male.

finding-nemo

2. The Lion King

Rafiki is introduced to us in the Lion King, where he performs Simba’s birth ceremony. He also sings a song in the film “Asante sana, squash banana, wewe nugu, mimi hapana”. This is a Swahili rhyme which translates to “Thank you very much (squash banana), you’re a baboon and I’m not!”. Rafiki doesn’t belong to any species, he is a cross between a mandrill and a baboon, he has the colourful nose and cheeks of a mandrill and the mane and long tail of a baboon.

3. Up

In the film Up, Carl ties thousands of balloons to his house to go on an adventure to South America. However, the number of balloons he uses are not enough to lift a house. Estimating that the house weighs 45,000 kg, you would need over 3 million balloons!

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4. Inside Out

Inside Out personifies five major emotions; Joy, Sadness, Fear, Anger and Disgust which all work together to guide and protect their human (Riley). However, there are actually six core emotions, with Disney missing out surprise. These six emotions are found to be universally recognized and expressed across the world, even in remote tribes that would not have learned the meaning of such facial expressions elsewhere.

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5. Tarzan

After baby Tarzan was left alone in the jungle to be raised by gorillas, he eventually grows up and meets Jane who teaches him to speak English. Unfortunately in the real world, no matter how great a teacher Jane was, Tarzan would never have been able to talk. Scientists have described a critical period up to the age of 5 which is vital for language development. If children, like Tarzan, aren’t exposed to a human language in this time they will be unable to learn to speak later in life.

tarzan

6. Aladdin

Aladdin and Jasmine travel from Cairo (Egypt) to Athens (Greece) in one second on the magic carpet, meaning they would have to travel at 621 miles per second! The air resistance would be 100 million times larger than their weight, causing them to burn up, like when meteors burn up when they enter our atmosphere.

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7. Star Wars

Star Wars is well know for its fights in space, full of explosions, blaster and engine sounds. However, space is a vacuum, meaning that it is devoid of matter, there are no gases or air there. Sound can’t travel in a vacuum, as sound vibrations don’t work, therefore we shouldn’t be able to hear any sound.

star wars

8. The Good Dinosaur

In the good dinosaur, a young dinosaur by the name of Arlo befriends a human boy. Arlo is an Apatosaurus which lived around 151 million years ago. Human beings as we are or Homo sapiens only evolved between 200,000 to 100,000 years ago so in reality Arlo and his friend would have missed each other by quite a few million years.

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9. Finding Dory

When searching for Dory’s family in Finding Dory, we discover that Dory was born in captivity, in an aquarium. However, Dory is a species of fish known as the Blue Tang. This species can’t be bred in captivity and have to be caught from their wild home of coral reefs in the Indo-Pacific Sea.

dory

 

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#TryThisTuesday: Make your own Sherbet

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sherbet

This week we’re taking on the science of sweets! Here is a super easy way to make your own sherbet powder at home.

All you will need is:

  • 7 teaspoons of sugar (either caster sugar or icing sugar)
  • 1 teaspoon of bicarbonate of soda
  • 3 teaspoons of citric acid in powder form

Mix your ingredients in a bowl and then take a small amount on a teaspoon and have a taste. It should fizz in your mouth.

Where does the fizz come from?

When you place the mixture on your tongue it reacts with the water in your mouth and produces carbon dioxide, this causes the fizzy feeling.

sherbet-equation

The reaction occurs because  acids, like the citric acid used here, release charged hydrogen particles when added to water. These particles will attack an alkaline (the opposite of an acid) such as bicarbonate of soda. The reaction produces more stable molecules – water and carbon dioxide.

If you pour water onto your mixture you should be able to see the reaction that’s happening in your mouth. You can actually feel the carbon dioxide gas being released if you hold your hand close to the surface.

7 Senses you aren’t taught in school

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Everyone is taught in primary school about our 5 senses – hearing, sight, smell, touch and taste. But did you know we actually have several secret senses? You might not even be consciously aware of some of them, yet you use them everyday.

1. Balance

balance

Most of us manage to stay upright on two feet without falling over. You can probably stand on one leg or in a unusual stance for a period of time without toppling. This is all due to our sense of balance or equilibrioception. You balance is kept steady by the level of a fluid in the vestibular system in your inner ears.

Try testing your balance – Stand with your heels and back against a wall, then try to bend forwards. You’ll find you won’t be able to or you might fall over. When you bend forwards, your bum needs to stick out behind your feet in order to stabilise your centre of balance and stop you tipping over.

2. Heat

heat

When you’re near a fire, you’ll be able to feel the heat on your skin even though the fire isn’t touching you. This heat, as well as the absense of heat, is detected by thermoceptors in your skin.

Thermoception aids your body by giving the correct response when you start getting too hot or too cold. For example, when you’re cold the hairs on your arms will stand up, this response has evolved as it helps to trap air and give you an extra layer of insulation, although nowadays you can probably just put on another jumper.

3. Painpain

Nociception is the perception of pain throughout the body, whether it’s a physical cut or damage to an internal organ. It signals to your body that there is a potential threat and calls for an appropriate response.

4. Body Awareness

proprioception copy

This is a sense you will use all the time but you’ve probably never even thought about it. Also called, proprioception, it is the unconscious awareness of where your body parts are in space and in relation to the rest of you.

Test your proprioception by closing your eyes and touching your nose. Despite not being able to see your hand or nose, I bet you were pretty accurate in finding it?

5. Electrocreception

shark

This isn’t a sense that you have but lots of marine animals commonly use electrorecption to hunt for food. Sharks take advantage of the high conductivity of salt water, their electrorecptivity allows them to detect the electric signals produced by the activity of fish. Duck billed platypus, believe it or not, hunt in a similar way to sharks as they have thousands of electroreceptors in the mucous glands on their bills.

6. Echolocation

beluga

Bats are famous for their echolocation abilities. Although they aren’t completely blind, they hunt at night when it’s almost impossible to see and so echolocation evolved as an alternative to sight to help them navigate. They produce sounds so high pitched, we can’t usually hear them. This sound echos and bounces back to the bats, they use the returning noises to build up an internal image of their surroundings.

They’re not the only ones with this impressive talent, if you’ve seen Finding Dory, you may have noticed Bailey the Beluga Whale also uses echolocation. Belugas use a fatty deposit, known as a melon, on their head to target their sounds in different directions.

7. Magnetoreception

pidgeon

Many birds have the ability to detect magnet fields. This sense is called magnetoreception and is used to help birds find their way on long migrations. No one is quite sure how birds detect or see magnetic fields but there are hypotheses that suggest they use either a protein called cryptochrome or the highly magnetic compound, iron oxide.

Interestingly human eyes contain cryptochromes but we aren’t able to utilise the protein to detect a magnetic field.

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