Tag Archives: try this at home

Bonfire Night | The Science of Fire

Remember, remember the 5th of November, gunpowder, treason and plot! We see no reason why the science of fire should ever be forgot!

For this bonfire night, we are looking into the gravity defying properties of water using fire!

Step 1

Pour the water into your container and add the food colouring to colour the water to whatever colour you like, we chose blue.

Step 2

Place the candle in the middle of the water but make sure the wick and wax of your candle stays dry.

Step 3

Get an adult to help you light the candle and make sure the wick is burning for about 20 seconds before moving onto step 4.

Step 4

Place your glass/plastic cup over the candle, this will push all the water away from the candle

Step 5

Wait for a few moments and watch the candle go out and the water rise on the inside of the cup!

The science!

First of all, why does the candle go out?

Fire needs three things to burn; oxygen, fuel and heat. These three things make up the fire triangle which you can see below.

If one of them is taken away, the fire is put out. By putting the cup over the candle, the oxygen is taken away from the fire so it goes out!

But… it doesn’t go out straight away. This is because there is still some oxygen trapped inside the cup but once the fire has used up all the oxygen there is none left so the candle goes out.

So, why does the water in the cup rise after the flame goes out? When the candle is lit, the particles in the air take in some of the heat from the flame and get hotter. When the particles get hotter, they have more energy so move faster and this increases the pressure inside the cup.

After the flame has gone out, the particles cool down and move more slowly and this decreases the pressure in the cup. The pressure outside the cup is then higher than inside the cup so the water is pushed inside the cup until the pressure outside the cup is the same as the pressure inside the cup.

#TryThisTuesday: Virtual Treasure Hunt

To celebrate International Talk Like a Pirate Day we have put together a virtual treasure hunt that you can do from a phone or computer.

For this treasure hunt you will need to solve clues to find co-ordinates to the next stop . The first three people to make it to the end of the hunt will win the treasure of a Street Science Busking Kit which is filled with equipment to make amazing science demonstrations at home!

Using Co-ordinates

Geographic co-ordinates allow every place on Earth to be identified with a set of numbers. The system that we’re using for this treasure hunt gives every point a latitude number and a longitude number.

If you were to draw a line from your point on the globe into the centre of the Earth and another from the centre of the Earth to the Equator, the angle between these two lines gives you the Latitude.

Longitude is measured slightly differently.  There is an invisible line running from the North Pole to the South Pole through the Royal Observatory in Greenwich, London, known as the Prime Meridian.  All points along this line have the longitude 0. The longitude of other points are calculated as the angle east or west from the Prime Meridian.

So Newcastle Upon Tyne, where we’re starting our treasure hunt from, has the co-ordinates 54.97, -1.61 because it is 54.97 degrees from the Equator and 1.61 degrees to the west of the Prime Meridian. Going west of the Prime Meridian or south of the Equator gives the co-ordinate a negative value.

 

The Treasure Hunt

Try to solve the clues to find the co-ordinates for the next place. Once you’ve got co-ordinates type them into Google maps (just like this: 54.97, -1.61 with latitude first) and make a note of where you’ve got to.

This will test your research skills as well as your maths skills, feel free to use Wikipedia and a calculator.

Destination One

The latitude for the first place is 57.14 divided by the number of universities in Newcastle Upon Tyne.

The longitude is  equal to 10 – 90.65.

Where are you?

 

Destination Two

To find the latitude of our second destination, take the last two digits of the year the first man walked on the moon, half this number then add 3.32

The longitude can be found by taking the year Newcastle University became independent from Durham University away from the year that the oldest part of the university (the School of Medicine and Surgery) was established and adding 6.52.

What amazing feat of engineering are you near?

 

Destination Three

For the latitude of our next place, take away 3.1 from the distance that Destination Two stretches in miles.

The longitude can calculated by the number of different countries that students at Newcastle University have come from divided by -2.

Which wondrous forest have we arrived at?

 

Destination Four

The latitude of this place can be uncovered by multiplying the number of countries that share Destination Three by 5 then adding 1.234

The longitude is equal to the number of reptile species that have been discovered in our previous destination divided by 63 then add 0.053

What amazing discoveries were made here?

 

Destination Five

The above place is often known by an abbreviation of four letters. If you convert these letters to numbers (eg. a=1, b=2, c=3 etc.) and square the second number, then add 0.197 you will have the latitude of our next  destination.

To find the longitude, convert the first letter of the abbreviation to a number and take this away from 58.274.

Which incredible man made structure are you looking at now?

 

Destination Six

For the latitude of our final place – where the treasure is buried – you will need to divide the total height of the structure we just saw (in metres) by -46.1.

To find the longitude, simply take away 16 from the number of floors in this structure.

Where is our treasure buried?

If you think you’ve cracked it, either send us an email to stem@ncl.ac.uk or comment below with the six places the co-ordinates led you to!

 

#TryThisTuesday: Rice Bottle

Our #TryThisTuesday this week, is a challenge for you. The task is to fill a dry bottle with rice and lift it up using only a pencil.

Have a go or challenge your friends, once you think you’ve cracked it (or given up) scroll down to see how we did it!

The Solution

Take the lid off the bottle and push the pencil half way into the rice. Take the pencil out again and push it back in, repeat this about 10 times. Eventually, when you pull the pencil to take it out, the bottle will lift up with it!

This occurs due to the force of friction acting on the pencil and holding it in place. When you first pour the rice into the bottle, it will arrange itself with lots of gaps but every time you insert the pencil you push the rice down making it more compact or dense. Some grains may even break or change shape under impact with your pencil. The more you do this, the greater the surface area of rice that comes into contact with the pencil. This gives a greater force of friction. Friction is a force of resistance between two objects when they  move past each other. The force is so strong at this point that it doesn’t allow the pencil to slip past the rice and so the rice (and the bottle) moves with the pencil as you lift it.

In the Real World…

This works in a similar way to quicksand. If you were to step onto quicksand, you would compact the particles, making them move closer together and lock around your foot, pulling you in. The friction makes it difficult for you to pull your foot out. Don’t worry too much though – quicksand is much denser than a human being so you wouldn’t be able to completely sink in it. As we learnt from our ketchup packet submarine and the oil and water experiment – less dense substances float above denser substances so you would stay above the surface of quicksand!

#TryThisTuesday: Cup Drop

For the week’s science demonstration, you will need a metal mug or screw, a pencil and string.

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  1. Tie one end of your string onto the handle of the mug and the other to your bolt.
  2. Hold onto the screw and pick up your pencil with your other hand.
  3. Lift up the string with the pencil and hold it about half way along the string, on the same level as the screw, allowing the cup hang down.

What do you think will happen from this position if you let go off the screw?

You may think that the cup will simply fall to the floor due to the pull of gravity and the string will pull the screw along, leaving you holding a pencil mid-air.

In reality, nothing (hopefully) hits the floor. You are right in thinking, gravity wants to pull the cup down, but it also wants to pull the screw down too. As the cup begins to drop it pulls the string, pulling the screw in towards the pencil, as the screw is being pulled from two directions it ends up swinging towards them. As it has a bit of weight behind it, it builds up enough momentum to go around the pencil a few times, wrapping the string around it.

So now the string is wrapped around the pencil and the cup still hasn’t dropped. If you try to pull the screw now, you’ll see why. It’s difficult to move the string. This is due to the force of friction. Friction is a force that occurs between two objects, it is the resistance that occurs when they move over each other. As the string is wrapped around the pencil a few times, there is a larger area of string touching the pencil, so a greater force of friction. This keeps the string in place to stop it sliding off, allowing the cup to hit the floor.

Try this out with your family and friends, see if you they can guess it correctly!

#TryThisTuesday: Rock Candy

This weeks Try This Tuesday takes a while, but you end up with a tasty treat!

You will need:

  • A wooden skewer or chopstick
  • Peg
  • 1 cup of water
  • 2-3 cups of sugar
  • A narrow glass or jar

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Clip the wooden skewer into the peg so that it hangs down inside the glass and is a couple of centimetres off the bottom.

Put the water into a pan and bring it to the boil. Pour about a quarter of a cup of the sugar into the boiling water and stir until it dissolves.

Keep adding more and more sugar, each time stirring it until it dissolves, until no more will dissolve. This might take quite a while!

When no more sugar will dissolve remove it from the heat and leave it to cool for about 20 minutes.

Pour the sugar solution into the glass or jar almost to the top. Then put your skewer back into the glass so it hangs down and doesn’t touch the sides.1st

Leave your glass in somewhere it won’t be disturbed. The sugar crystals will grow over 3-7 days. Once these have grown you can eat them!finished-product

The Science

By mixing the sugar and water together when they were really hot, you have created a super saturated solution. This means that the water contains much more sugar than in could in normal circumstances. As the water cools back down the sugar leaves the solution (mixture) and becomes sugar crystals again, forming on the skewer.

Supersaturated solutions are used in real life. In a sealed fizzy drink the drink is saturated (full) with carbon dioxide, as the carbon dioxide is put in using pressure. When you open the drink, the pressure of the carbon dioxide is decreased, which causes your drink to be supersaturated as there is much more carbon dioxide dissolved than there would be at normal pressure. The excess carbon dioxide is given off as bubbles.

#TryThisTuesday: Chicken Sounds from a Cup!

This week we are going to make chicken sounds from a cup!

You will need:img_4715

  • plastic cup
  • string
  • paperclip
  • paper towel
  • scissors
  • water
  • pin

 

 

 

First put a hole in the top of your cup. We found it easiest to push a pin through and then make the hole larger with scissors.

Cut a piece of string that is about 20cm long and put it through the hole in the cup.

Tie the top end of string to the side of the paper clip.img_4716

Wet the paper towel. Hold the cup in one hand and wrap the paper towel around the string near the paper cup. Squeeze the string and pull down in sharp jerks to make the chicken noise!

The Science

Sound travels in waves, which cause particles to vibrate and causes the sound. The vibrations from the string would normally be almost silent without the cup.

When you add the cup it amplifies the sound and makes it much louder. This is because the cup is a solid object, and there are lots of closely squashed together particles in a solid object for the sound waves to hit and vibrate. The more vibrations the LOUDER the sound.

 

#TryThisTuesday: Curly Fries!

Today we are looking at the science behind curly potato fries. First, let’s talk about how we make them.

  1. Carefully chop up a potato into straight thick chips.
  2. Boil around 250ml of water and stir salt into this water until no more salt will dissolve.
  3. Fill a bowl with tap water and place half of your chips into this bowl.
  4. When the salty water has cooled pour it into another bowl and add the rest of your chips to this.p1020750
  5. Leave both bowls of chips out overnight.
  6. The next day you should have one bowl of chips that are still hard and straight and the other bowl (with salty water in) will be full of chips that are more flexible, that you can shape into curls.

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The Science

The addition of salt to the water allows you to make curly fries due to osmosis. Osmosis is the movement of water from an area that has few molecules in the water to an area that has more molecules in it to try to even things out and create a balance.

waterin

Plants like our potato here are made up of millions of cells that have a cell membrane around its edge which allows some things in and not others. Water can easily flow through this but the salt we dissolved in it can’t. Cells are filled with lots of little molecules so water usually flows into the cells and fills them to dilute the liquid. But when we have lots of salt in the water, there are more particles in the water outside of the potato cells than inside so the water leaves the cells.

waterout

bendyWhen cells are filled with water they are quite rigid and packed closely together making a fairly sturdy chip. When the cells are dehydrated, they are smaller leaving space between cells, allowing the chip to bend without snapping.

Osmosis is used in all plants – not just when you cut them up and put them in a bowl of water! Plants use osmosis in their roots to allow water to move from the soil into their roots.

 

#TryThisTuesday: Making coins shiny again

New coins are always bright and shiny but they quickly become dull and tarnished. Today we are going to make our coins shiny again!

You will need 100ml of vinegar, some tarnished copper coins and a bowl.vinegar

Pour the vinegar into the bowl and add the salt. Mix until the salt is dissolved.

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Try dipping a coin in and holding it there for 5 minutes. See how half becomes really shiny!

half

Put all your coins in and leave for 30 minutes. If you put lots of coins in the vinegar may turn green.img_4337

Make sure you rinse all the coins with clean water.

The Science

Coins become dirty due to oxygen in the air reacting with the metal to form copper oxide. They become darker as they age as the oxide layer increases. Vinegar is an acid (acetic acid) which can be used to clean up surfaces and remove the unwanted oxides. Acids release positively charged hydrogen atoms, also known as Hydrogen ions (H+) which react with the negatively charged oxygen in copper oxide and produce water (H2O). The copper that was linked to the oxygen dissolves leaving a nice shiny surface.

If your vinegar turned green this is due to all the copper dissolving and producing copper acetate.

Real World Applications

Iron that is used to make cars, trucks and boats can also react with the oxygen in the air and oxidise, producing rust. If a car gets rusty, mechanics can use phosphoric acid  to remove it. It reacts with the rust, removing the oxide and replacing it with a layer of iron phosphate. This also protects the metal from rusting further.

Phosphoric acid is also found in coca cola, which is why it is so good at dissolving your teeth!

#TryThisTuesday: Oil and Water

For this experiment all you will need is a clear bottle or jar with a lid, water, cooking oil and some washing up liquid.

img_4313

Fill the water bottle half full with water.

Pour about 100ml of oil in to the bottle and observe what happens.

The oil should float on the water. Try and mix them together or challenge other people to mix them! It is impossible, the oil and water always separate out again.

Add a squeeze of washing up liquid to the bottle and shake. The oil and water now mix together.

The Science

Oil is less dense than water so floats on top. Oil and water don’t mix together as the water molecules are more attracted to each other than the oil molecules. Oil molecules are hydrophobic or ‘water-fearing’.

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Washing up liquid molecules are attracted to both water and oil. When you add a squirt in, one end of the washing up liquid molecule attaches to a water molecule and the other end attaches to an oil molecule. This creates a mix of water with oil droplets spread throughout it. This is because one end of the washing up liquid molecule is hydrophobic (water fearing) and one is hydrophilic (water loving).

The washing up liquid acts as a stabiliser and creates an emulsion. This is a mixture of two liquids that wouldn’t normally mix.

colloid1

Real Life Applications

We use washing up liquid when we are washing up as it attaches to the oil on the dirty dishes and lifts it off into the water.

Animals that live in the ocean also stay warm by producing an oily substance on their fur or feathers which keeps the cold water away from their skin.

#TryThisTuesday: DIY Sci-Fi Laser Sound

This week we will show you how to create sci-fi laser sound effects using a slinky and a cup.

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The first step is to try and listen to the noise a slinky makes on its own by moving it up and down so the bottom of it bounces off the floor as shown in the picture below.

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The next step is to place the cup in the top of the slinky as shown below and try the same movement.

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The Science

Sound is actually particle vibrations and travels in waves. This means it relies on particles colliding to transfer the sound energy. In a gas such as air the particles are really spread out which means they are less likely to collide. In solids the particles are much closer together which means the particles collide a lot more and the sound energy is transferred more effectively.

partic

This is why the sound is much louder when the sound waves travel through the solid cup as opposed to the air. Rumour has it that they actually used this same technique to make the laser sound effects in the original Star Wars movies back in 1977.