Science Showcase

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Fun with Rockets

Today was our last Science Club session for 2010 so we ended it with a BANG by making 2 different types of rockets.

One rocket was made out of a plastic bottle and an air pump. The other rocket was made by putting baking soda and vinegar in a film cannister. Both rockets work the same way really. As the rocket container fills up with gas (air or carbon dioxide) the pressure builds up. When there is so much pressure the cork pops out or the lid pops off and the rocket flies into the air.

Pumping air into the rocket. Everyone is getting ready to catch the rocket when it lands.

Shikar
Today I had a go at bottle rockets. I made 4. On my third one I pumped for a long time but as soon as I gave up and sat down, the rocket blasted off about 20-25 metres above the ground. I got to perform 2 of my rockets in from of an audience of junior kids. They liked both of mine. On one of my rockets, when it shot of some water splashed onto my shorts and new jersey. Mum won't be happy!

I learnt a new thing today! When the water was in the bottle the air I was pumping was making pressure. If you have lots of water or not water the bottle will only go about 5-10 metres high above the ground. I wonder what will happen if we put vinegar instead of water?

Alice
When we did the experiment we had an air pump, a bottle and water and a cork. First of all we filled quarter of the bottle with water. We used the air pump to fill up the bottle with air pressure. When the bottle is filled up with air pressure it shoots up into the sky.

This photo shows how to get the rocket ready by jamming the cork into the bottle.

Alana
To launch the big rocket you need to pump the pump to make it fly up. Make sure you stand far away unless you are launching it. You can fill the bottle up with as much water as you want but we found that it works better when the bottle is quarter full. If you're finding your rocket is taking a long time to blast off it means it should go higher. It works because the air getting pumped into it fills up the bottle and when there is not enough room left it pops the cork off the bottom.

Jack
I found out that the best rockets were the big bottles with water up to the first line from the bottom. This is because there was enough water and enough room for the air pressure to help push but not too much water to weigh it down.

Max
The rocket made from a lemonade bottle quarter filled with water worked the best. I think this worked because there was lots of space for air to go so when the bottle was full of air the cork came out really fast, giving it a height boost.

Billy
Today I had a go at making bottle rockets. To make a bottle rocket you have to fill a lemonade bottle quarter full with water. The rocket is powered by the water and the water acts as a jet because it pushes the bottle up. AWESOME.

Harrison
My rocket went wild. It was facing north and it landed west. Totally opposite. All of mine worked except one. The pipe busted but we fixed it. The rocket worked because the water in the bottle was taking up space and there was no more room for the air we pumped in. So there was too much air and the cork flew off and the air pushed it up into the air.

Louise
We used a foot pump and we could see the air bubbling up inside. The rocket worked because it had too much air pressure so it had nowhere to go but up. The worst working bottle was the vinegar bottle and the best bottle was the lemonade bottle.

Cameron
First we got a bit of baking soda and wrapped it in a tissue and put in in the film cannister. Then we got the vinegar and tipped it in and quickly put the lid on. After a while the cannister pushed the lid off and it went really high.

The experiment worked best when there was less baking soda, less vinegar and if you put the lid on quickly.

What effect does friction have on rolling marbles?

WHAT IS FRICTION?
Friction occurs whenever 2 surfaces move against each other. Friction tends to slow movement down.

Sometimes we want lots of friction (eg - so car tyres grip the road, so our shoes don't slip on the floor, so our hands don't slip off the cricket bat).

Sometimes we don't want friction (eg - on a water slide, when we are skiing or ice-skating).

This week the middles have been finding out about which type of surface has the most friction. We tested this by rolled a marble down a ramp then onto different types of surfaces. When the marble stopped rolling we measured the distance it had rolled.

The test surfaces were:

• carpet
• cardboard
• newspaper
• towel

Which surface do you think let the marble roll the furthest?

This is what the marble ramp looked like. In this photo we are testing the cardboard race track.
We let the marble go at the top and watched it zoom down.

Next we had to measure the distance that the marble rolled. We had to use our maths skills to measure accurately and add up the measurements when the marble rolled further than the length of the ruler.The whole team had to work together on this task.

WHAT DID WE FIND OUT?

We found out that the cardboard race track let the marble roll the greatest distance. We think this is because the cardboard is really smooth so there is not much friction gripping onto the marble to slow it down.

The worst race track was the towel. The towel is really rough and has lots of fibres sticking up. These fibres grip onto the marble creating lots of friction. The marble can't roll very well at all.

Mini Investigations

This week at Science Club Miss Harrison set out a range of mini science investigations for us to have a go at. We had to think about what was happening and come up with an investigation.

This is what we did and found out.

Compression of Substances - Louise
There was the following in syringes - water, salt and air. The hardest to press down was the water and the easiest was the air. Because the end of the syringe was blocked the water needed to go somewhere and it went nowhere so it was the hardest.

Air Takes Up Space - Jack
For this experiment you only need a piece of cardboard, a water tap and a small round container or cup. Fill the cup with water (3/4 full) and put the cardboard over the cup. Tip it upside down. Now let go of the cardboard and hold the cup. The cardboard will stay. This is because the water is pushing down but because the air pushes in all different directions it pushes up and keeps the cardboard on the cup.

Making a rainbow with a Prism - Billy
To make a rainbow with a prism is easy. You get a clear prism and point it at the sun or a light. You see some things in rainbow vision. It is really cool.

Observing a lighted candle - Shikhar
First we lit a candle with a lighter. Then we observed the candle in different ways (eg - blowing, turning upside down and trying to make it go out without blowing or touching it). The bottom of the flame is blue and sometimes white and the top is yellow. This middle is usually orange or red. If you press the very little flame with your fingers it can go out without hurting or burning your fingers. Be careful though. Fire is a very interesting and amazing element.
Air takes up space - Harrison
Put a tissue in a cup and stick it in so it stays at the bottom.
Put the cup with tissues upside down in water.
Take it out.
What happened?

• The tissue is dry. There is still air in the cup so the water can not go in.
• If you put the cup in the water sideways, water will go in.

Air Pressure - Russell
We had 2 syringes and a tube joined onto both of the ends. This experiment worked by air pressure. When you pushed the air out of one tube it makes all the air go into the other tube, making the other tube go up.
Putting a jar over a burning candle - Ella
We lit a candle standing up in a bowl of water. Then we placed a jar over the candle. After the candle burnt up all the oxygen the candle went out and the water rose up into the jar to take the place of the oxygen.

Putting a jar over a candle - Cameron and Bradley
This experiment was to fill a bowl up with water, put a lit candle in it and cover it with a jar. Then we had to see what happened.
The candle starts to die down and the water starts to rise. This happens because there is no oxygen and there is lots of space for the water to come in.

Solar Panel animations

May the force be with you

This week the Year 3 and 4 classes learnt how to use a forcemeter to measure the force it takes to do different jobs.
This picture shows a forcemeter being used to see how much force is needed to do the job of lifting up a bucket of weights.

The forcemeter has a spring inside that is pulled down as force is applied to the object. The force is measured in Newtons (N) which is named after Isaac Newton.

We also tested how much force was need to...

• lift a school bag
• lift a shoe
• lift a cup
• open the door

Next we got to make our own forcemeters which we called Pull-o-meters. We had to be good at using a ruler to measure out each section.

Instead of using a spring our forcemeters use a rubberband. When the load is hung on the hook the rubberband stretches and we can read the scale to find out the amount of force being used.


Next we used our forcemeters to see if lifting, pulling or rolling a weight used the most force.
We found out that lifting used a lot more force that pulling or rolling. Our explanation for this is that when you lift something off the table gravity starts pulling it back down which makes it hard to lift. When you pull or roll something the object is being supported by the table.

Moo Glue

Did you know that you can make glue from milk? Today in science club we found that it can be.

After reading about it in a school journal we discovered that in the past and in different cultures glue is made from lots of things such as plant saps, animal bones and hides, cassava root, bread fruit and other vegetables.

The article also talked about a class who made their own glue from milk. We decided to try it out.

Casein is a protein that is found in milk and was used by ancient Egyptians as a glue for boat building and to weatherproof aeroplanes during WWII. Casein is what makes the moo glue work.

To get the casein you add vinegar to milk which makes the milk separate into solids and liquids. The liquids are called whey and the solids are called curds. The curds are full of the protein called casein.

The vinegar curdles the milk. They whey is drained off to leave the curds behind.

Most people thought the curds looked disgusting but soon they were happy to touch and squeeze them.

The next step involves adding baking soda and hot water to the curds. You have to mush up the curds and stir for a long time to turn the mixture into a glue.

The moo glue still didn't look like it would stick things down so we tested it out. These are some of the pictures we made. We think they look great. And yes, the glue did work (mostly!)

Do heavy objects fall faster than light objects?

This week the Middle syndicate has been learning about Gravity. Gravity is the force that pulls all objects down towards earth. If we did not have gravity we would all be floating around and life would be pretty hard.

Imagine a bowling ball and a soccer ball. They are the same size and shape but the bowling ball is heavier than the soccer ball. If you dropped them both from a high place at the same time which would hit the ground first?

Most of the children in the Middle syndicate thought that the heavier bowling ball would hit the ground first. So to find out we did an investigation.

We tested pairs of objects that were the same size and shape but different weights. We then held them out level and dropped them at the same time. It was hard trying to decide which object hit the ground first or if they landed together.

We recorded our results on a chart.

Overall we found out that the objects fell to the ground at the same time. This is because size and shape affect how objects fall not weight.

Some people thought that if the objects were different sizes they would fall at different speeds. So we tested this using a flat piece of paper and a screwed up piece of paper. The screwed up piece of paper hit the ground first and the flat piece of paper floated down slowly. WHY?

After thinking about this for a while we decided that...

• Objects that are the same size and shape, but different weights, fall at the same speed because they can push through the air.
• If 2 objects are different shapes but the same weight they will fall at different speeds because the air slows bigger objects down.

Science was hard this week but Miss Harrison was impressed with all the good thinking and explaining that the students did!!!! WELL DONE.