Primary Science Week 2013
Activity 5 Friday- Last Day!!
#1 Water Molecules on the Move
This experiment is great for testing if hot water molecules really move faster than cold ones. Pour some water, drop in some food coloring and compare results.
What you’ll need:
- A clear glass filled with hot water
- A clear glass filled with cold water
- Food coloring
- An eye dropper
- Fill the glasses with the same amount of water, one cold and one hot.
- Put one drop of food coloring into both glasses as quickly as possible.
- Watch what happens to the food colouring.
If you watch closely you will notice that the food coloring spreads faster throughout the hot water than in the cold. The molecules in the hot water move at a faster rate, spreading the food coloring faster than the cold water molecules which mover slower
#2 Mixing Oil and Water
Some things just don’t get along well with each other. Take oil and water as an example, you can mix them together and shake as hard as you like but they’ll never become friends…..or will they? Take this fun experiment a step further and find out how bringing oil and water together can help you do your dishes.
What you’ll need:
- Small soft drink bottle
- Food colouring
- 2 tablespoons of cooking oil
- Dish washing liquid or detergent
- Add a few drops of food colouring to the water.
- Pour about 2 tablespoons of the coloured water along with the 2 tablespoons of cooking oil into the small soft drink bottle.
- Screw the lid on tight and shake the bottle as hard as you can.
- Put the bottle back down and have a look, it may have seemed as though the liquids were mixing together but the oil will float back to the top.
While water often mixes with other liquids to form solutions, oil and water does not. Water molecules are strongly attracted to each other, this is the same for oil, because they are more attracted to their own molecules they just don’t mix together. They separate and the oil floats above the water because it has a lower density.
If you really think oil and water belong together then try adding some dish washing liquid or detergent. Detergent is attracted to both water and oil helping them all join together and form something called an emulsion. This is extra handy when washing those greasy dishes, the detergent takes the oil and grime off the plates and into the water, yay!
Activity 4 Thursday
This is the way window-cleaning sprays and perfume atomizers work.
What to do: About one—third of the distance from one end of the straw, cut a horizontal slit. Bend the straw at the slit and slip the short section into a glass of water, keeping the slit about 1⁄4 inch (6 mm) above the surface of the water.
Blow hard through the long section of the straw.
What happens: Water enters the straw from the glass and comes out through the slit as a spray.
Why: As you blow through the long section of the straw, a stream of air flows over the top of the short section, reducing the pressure at that point. As normal pressure underneath forces water up into the straw, the moving air blows it off in drops. In atomizers and spray cans, you use a pump to blow in air.
Activity 3 Wednesday
Balancing Act – Cylinder Strength
A piece of paper uses physics to balance a textbook… and much more!
If someone told you that they could balance a full-size text book on a piece of paper, you might call up the looney bin. That’s a crazy idea, right? Well, the notion that a book can sit, precariously, atop a plain piece of paper isn’t quite as bonkers as you might think! With a little knowledge of physics and geometrical shapes, you can perform the Balancing Act, too.
- Piece of paper
- Rubber band
- Other items to balance
(You choose. Be creative!)
- Try to balance the textbook on a rolled up piece of paper. Use whatever method you want, but we’ll bet you can’t do it! Try rolling the paper up, making an arch… try everything.
- Now roll the paper into a cylinder, length-wise, and wrap a rubber band around the tube to hold it in shape.
- Now try balancing the textbook on top of the paper cylinder. Like magic, the tube can now support the entire weight of the textbook!
- Looking at the cylinder, you might think the paper cylinder could support way more weight than just the textbook. There’s only one way to find out! Find other items to balance on top of the text book. It’s probably a good idea to keep the items unbreakable, because at some point, you’ll have too much weight on there.
- How many items were you able to get on top of the paper cylinder before it collapsed?
How does it work?
The average weight of a standard, flimsy, white piece of printer paper is less than 1 gram, right around .7 grams. It would make sense that something that light isn’t able to hold the weight of a text book. Just trying to balance a textbook on top of the paper doesn’t work… the paper just collapses! This is because the paper is unable to keep it’s shape. It wants to return to a flat piece of parchment. With the addition of a rubber band, though, the paper can support and balance the textbook, and a whole lot more!
The secret to the paper’s new found strength is the geometrical shape known as a cylinder. Cylinders are one of the most structurally sound, and strongest, geometrical shapes. Cylinders are able to be incredibly strong, regardless of the material they’re made out of, because they disperse stress throughout their entire shape. If the rolled-up piece of paper were a perfect cylinder, the strength would be even stronger!
Adapted from Steve Spangler Science: http://www.stevespanglerscience.com/content/experiment/balancing-act-cylinder-strength
Make your own Oboe – in less than 1 minute!
Quite a few people learn to play a musical instrument but very few learn to make one! We’re about to make our very own straw oboes and it’ll only take a minute.
WARNING: – This activity uses scissors, watch out your pointy straw will be sharp and is designed to make sound
What do I need?
• A straw (any old one will do – variations or modifications can be done as follow-ups with different sized straws to change the sound produced)
• A pair of scissors
How do I do it?
1 – Flatten the end of the straw (last 2 cm) down as much as possible with your nails.
2 – Cut the end of the straw into a point as shown to the right.
3 – Make sure pointed end of the straw is open just a little bit (see far right image).
4 – Blow gently through the pointed end of the straw.
This can take a few minutes to get the hang of as you find the right position in your mouth. Start with straw about half-way along your tongue (do not gag yourself) and as you blow out through the straw, slowly pull the straw out of your mouth to find the position that makes noise. When you get it right, what happens to your lips?
What’s going on?
Every single noise in the whole world works the exact same way. From children talking when they shouldn’t! To the best musicians in the world! Whenever you hear a noise you know something must be vibrating (just another way of saying shaking). In this case it’s the straw itself that’s vibrating and making that beautiful noise.
For more details about the science involved go to: http://www.phys.unsw.edu.au/jw/woodwind.html
More Fun Please! – Experiment like a real scientist!
• First of all get the hang of playing your brand new instrument!
• Next up, see what happens to the sound when you make the straw shorter (just cut it shorter!).
• What happens when you blow it harder?
• Keep your eye out for thicker and thinner straws (when you’re out and about) and see if you can hear a difference between them?
“The most exciting phrase to hear in science, the one that heralds the most discoveries, is not ‘Eureka!’ (I found it!) but ‘That’s funny…’ – Isaac Asimov
Adapted from: http://www.sublimescience.com/DontEatYourSlime.pdf
For this activity, please find two different-sized straws. Make sure one is skinny (like a coffee stirring straw) and one is fatter (like a soda straw). Or use rolled up pieces of paper of different sizes.
Put the big straw in your mouth and plug your nose. Try to breathe only though the straw for 30 sec. Can you do it? What did it feel like?
But what if you had asthma? Would breathing always be so easy? Let’s find out…
Now pick up the skinny straw. Put it in your mouth and plug your nose like before and try breathing only through the straw. What does it feel like? Is it harder or easier to breathe through the skinny straw?