# Jaydeep (7) asked “Why do sponges absorb more hot water than cold water?””

Thanks team. I agree with you I don’t have an answer to Jaydeeps question. I think the best I can do is try to carry out an experiment to test the observation that you have made.

I would need a sponge (natural or manufactured), a fixed amount of water and a way of drying the sponge. If we are going to do a fair test the sponge must be the same for both the hot water and the cold water test. It also must be in the same condition (preferably dry). I would also need to be aware that you should weigh the water, the weight of hot and cold water must be the same. As water is heated the volume gets bigger.

Jaydeep …maybe you could also try the experiment above and see whether a sponge does absorb more hot water than cold water. You could let me know the result by telling me your result in the comment box below.

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# “How does speed affect the energy of motion during a collision?” asked Damián Muñoz (9)

Sorry Damian it doesn’t really answer the question you asked. They have just presented you with more questions.
Let’s look at what they said.

Firstly energy is about work. The Energy or Work associated with a moving car is its movement. This type of energy is called Kinetic Energy. We could change the car’s Kinetic Energy by making the slope steeper (move the slope up a rung). It will make it go faster.

How do we measure the energy it is gaining as it moves faster and faster down the slope? Yes it does go faster while it is on the slope (we say that it is accelerating). Remember it starts with no energy at all (not moving). When it reaches the bottom of the slope it is going at its fastest speed.

We could measure the energy by seeing how long it takes to stop moving when it reaches the bottom of the slope. Try it. Make sure the test is fair. Fairness is very important in science investigations.

Alternatively you could involve it in a collision at the bottom of the slope…..say some cardboard or paper and see how far the car can push the shape it collides with. That would be another way to measure the ‘work’ that the moving car could do.

Damian, think about it. Experiment, and let me know how you got on.

Science Master

# Lachlan(12) asks “How does a trebuchet work?”

Lachlan – my first question is what is a trebuchet?

Simple answer …It’s a type of catapult.

Here is an image of  a very early trebuchet

Here is an image that may help your understanding and give you some clues on how the trebuchet works. When the mass 1 is released it begins to accelerate towards the ground. In doing so a force is applied to the beam pulling it down. That force is then applied, via the beam to the mass 2. What do you think will happen to Mass 2?

The support for the beam, the fulcrum, is in a particular position. Any thoughts on that? You could create a see-saw and investigate the application of forces when the fulcrum  changes position ……altering d1 and d2.

# “Why does soft serve ice cream increase in volume in a milkshake as it’s melting?” asked Tim (13)

Thanks for your comments team. I’m afraid you are wrong. My research suggests that Soft Serve has less fat than ordinary Ice Cream. The real difference is the amount of air in the ice cream and the temperature at which it is stored. In my view it is the amount of air that is crucial.  When Soft Served is warmed I would suggest that the air in the fat which makes up the ice cream makes the ice cream expand to a greater extent than the ordinary ice cream.

You could try a little experiment to confirm this. Take two equal samples of ice cream (soft serve and ordinary) of the same weight (use kitchen scales). Let them warm up. Allow the ordinary ice cream to reach the same temperature as the soft serve (ordinary ice cream is usually kept at a lower temperature than soft serve). Make sure that the two samples are in the same kinds of containers. Do they expand to the same degree?

What do you think the role of the air is in this process?

I hope that this gives you a clue to any differences that you see.

# Liam Astra asks “Why does Mentos lollies make coke spurt everywhere?”

Liam, thanks for the question. Are you sure that you wanted to talk about Mentos lollies? I couldn’t find any mention of them …..only sweets …so I have focussed on them.

Let me start my answer by showing you my favourite clip of the Mentos/Diet Coke reaction.

My first question is ….is there anything special about diet coke and the Mint Mentos tablet?

Firstly there is evidence (somebody has done some experiments) that diet coke contains more carbon dioxide gas than ordinary coke. When they make coke they add carbon dioxide gas to it. Lots of gases are absorbed by liquids. Oxygen gas is absorbed by water…..this allows fish to breathe. The manufacturers add carbon dioxide to the coke because it enhances (makes better) the taste of the coke. Carbon dioxide, like oxygen is a safe gas  – it is the gas that you and I breathe out – it is created by our bodies.

Experiment 1.  Add a Mentos to a bottle of Coke and one to a bottle of Diet Coke….is the reaction the same? Make sure that it is a fair experiment (talk with others about how you can make it fair). Make sure that it is a safe (if you have them wear goggles) and a tidy experiment. (think about your parents or teachers)

Experiment 2. Now let’s look at the Mentos tablet. Is the tablet smooth or rough to the touch? Try and find something (maybe an adult can find you a little bit of sandpaper) that will change the surface of one of the Mentos tablets (more rough or more smooth) and drop it into a diet coke bottle. What happens? Do the rough and smooth tablets both give exactly the same ‘spurt’?

You could also carry out this experiment with Fruit and Mint Mentos tablets?

Here are some magnified photographs of the surface of a Mentos tablet.

So what have we found out? What has roughness to do with surface area? Why does the dissolved gas decide to come out of solution when it meets the tablet?

Let me know your thoughts in the box below.

# Will (8) asks “What makes seeds grow?”

Will, thank you for your question. Let’s start with some interesting questions. Answers to these might help in answering your question. Firstly is a fruit a seed?  If it is not a seed then what is it for? Does it help the seed grow? How will we know if the seed is growing? What does a seed need to grow? Does it need soil? Do seeds grow when it is cold? Do different seeds grow at different speeds? What do you think? Are there any more questions? Remember questions are what science is all about. By investigating questions you are building knowledge of the world around you.

So, let’s think about how we could investigate some of these questions. Shall we look at just one type of seed, or choose a variety of different seeds to investigate? Maybe looking at one type of seed would help us begin to answer some of the questions. We could then look at another type of seed and compare the results. Maybe one seed would grow faster than the other?

Now we have to think about the conditions for our growing experiment ….. soil/no soil, wet/dry, light/no light, hot/cold. Even for our selected seed this can be very complicated. Can you see why?

The investigation equipment could probably be obtained at home. A empty plastic bottle, with the top cut off, would be a good holder for the seed. Some cotton wool could act as soil. A cupboard and a refrigerator could also help you create the right environment.

Let me know how it went?

# Some Questions about the Solar System by Rishi, Ned, Maya, Thomas, Jackson, Adam and Pug.

Many thanks for the questions, and they are all about the Solar System. Amazingly I have just (three days ago) visited the Kennedy Space Centre in Orlando so they come at a time when I am excited by the science associated with space and space travel. I had questions before my visit and after it I had more. That’s the brilliance of these exhibitions, they raise questions. So let’s look at yours.

Rishi asked “How does the solar system work?”

I immediately think of why does it work in the way it does? The centre of the Solar System is the Sun. The Sun is one of a group of stellar objects called stars. Our star was named, by somebody, in the past, as the Sun.  Our star (the Sun) seemed to have attracted to it some massive lumps of matter/material which we call planets (planets are the biggest ‘lumps’ , the smaller ‘lumps’ are called asteroids and meteorites. What has given the Sun the ability to attract these ‘lumps’?

You then have the amazing thing that these lumps move around the Sun. They are attracted to the Sun but do not fall into it. They rotate around it, why do they do that? . Or does the Sun rotate around them?

So Rishi, your question is a great science question. From it lot’s of other questions arise, and that is what science is really about.

Ned asked “If the world split in half, would there still be a gravitational pull?”

Ned, thanks for the question. Gravity is one of those strange things called ‘forces’. Most forces are easy to define. You push things, you pull things by physically applying a force. Magnets  can push and pull so they can apply a force. So how can you explain the fact that things are somehow ‘pulled ‘ towards the Earth?  This seems to be something called a gravitational force. It’s strange. Nothing seems to be pulling or pushing you. Scientists have created a word called ‘gravity’ which describes the process of one object (of a big mass) pulling towards it a smaller mass.

We know that there is this force called gravity that exists. I am not sure that we have yet found out what causes it. We know that a very big object (of great mass) will attract a much smaller object (of smaller mass), however we have no idea why.

So at last to your question. My hypothesis (find out what that means). Slitting the world in half would mean that both halves of the Earth would move closer to the Sun because, the Sun is the biggest object in our Solar System.

Maya asked “What is the milky way?”

Maya, it’s a good question. I wonder who first used the name ‘the milky way’ and why? I firstly think about stars in the night sky, they produce white light (I wonder why – why not red or yellow light?). Does our star (the Sun) produce white or yellow light?

It is for a lot of us to really observe the night sky in all its glory. Why? It seems to be all the background light that we are experiencing when we look at the night sky. Go to a very dark place, away from the city, away from a near town and look at the night sky. You will see things you have never seen before. It is magical. You will see more stars than you have ever seen in your life. Only then will you see the Milky Way and only then will you know what it means.

Thomas asked “How many Suns are there in the universe”?

Thomas, thanks for the question. My first question is . What do you mean as Universe? As yet the investigation of the Universe in which we live is incomplete. We do not know how big it is. We do know, that the Universe consists of groups of stars that we have called Galaxies. We are in a Galaxy called the Milky Way (see Maya’s question). There are millions of stars in our Galaxy. So Thomas, in answer to your question ….we do not know …but the important thing is that you asked the question. By asking the question the quest and research for an answer continues. That is science.

Jackson asked “How big is Jupiter?

Jackson, a great question. It raised a question which I tried to find the answer to “Why do we want to know the size of Jupiter?’ I suspect it is to try to answer an even bigger question linked to Risha’s question. Why do the planets orbit the Sun? Is there some reason in there order of orbit …Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune?   Jupiter is the biggest planet in terms of mass and size in our Solar System . It would be nice if the size and mass of the planets and their orbital position was a straightforward order …but not so. That seems to be the outline of another question.

Adam, an interesting question, thanks.  It is thought that the Sun is 4.6 billion years old that is …would you believe it 4,600,000,000 years. Scientists reckon it was formed by the sudden compression of hydrogen and helium gas caused by the explosion of nearby star. Wow. This leads to lots of other questions …..think about them and let me know. The scientists also reckon that the Sun is about halfway through it’s life.

Pug asked “If all planets crashed into each other would it affect other Solar Systems?”

Pug, a good question. What do you think would happen if all the planets crashed into each other? How would it happen? Here is ia hypothesis. The most likely scenario would be the outer planets moving into a lower orbit and crashing into the lower orbit planets. They would then be affected by the gravitational pull of the Sun. They might then crash into the Sun. The Sun may therefore gain more energy and explode into a supernova. Pug, a hypothesis is an idea, can you come up with an alternative one? Let me know.

# Pete (10) asks “What is the pitch of a sound?”

Thank you team.  Lets first look at the motion of the particles. You suggest that the motion of the particles is in the form of waves. I think that is quite difficult to imagine but I think I have an example that will help illustrate this type of motion. Look at what happens when you drop a pebble in a pond. The pebble, when it hits the water, it creates  one vibration.

In this image the sound is produced by the piston creating the waves. Notice the wavelength, that is important. If we can manipulate the piston, make it go slower or faster  we can change the wavelength. Changing the wavelength is changing the pitch, think about that.  How does the sound change?

Try blowing over, or tapping, some bottles.

Pitch and Frequency ..Test your hearing a little bit more …….

In the video below you can see and hear how the pitch of the sound and the wavelength change together.  We measure wavelength in units called Hertz. 1 Hertz is one cycle per second. In the image above imagine that it takes one second to get from the flute to the ear. Then there are 8 cycles in the top sound is so frequency is 8 hertz and there are 3 cycles in the bottom sound so the  wavelength is 3 Hertz.

You can now test your hearing.    Take Care….make sure you have control of the volume.

Thanks to
Orion Lawlor, for the water ripples video, Published on 9 Jan 2011
Earmaster at https://www.earmaster.com/music-theory-online/
The ISVR from the Institute of Sound and Vibration Research, University of Southampton.
The Sound Video, unknown but thanks.

# Braiden (9) asks “What makes a diamond so hard?.

Braiden, my question (before I turn you over to my team) is how do you detect ‘hardness’? Can you create an order of hardness with some common materials?
Lets say:

wood (balsa)
wood (oak)
plastic object
bath sponge
china(cups and saucers)
glass
concrete pathway
cardboard
metal fork
coin
rock (sandstone)
piece of coal
pencil rubber
For obvious reasons I have not included diamond in this list. I think that would be an interesting experiment to carry out. You will have to make sure it is a fair test

Now over to my team.

Graphite has a layered structure with weak forces between the layers, This is a weaker structure than the close bonding of the diamond. The carbon atoms like the tetrahedral arrangement of the bonds with other carbon atoms. It is a very strong force.

Hope that makes some sense. If you have questions about the explanation please ask them. If you want to see my ‘hardness’ list go to Science Master Special-Hardness Results

# “How does sound travel in things other than air?” asks Lilly(12)

Hello Molly, Science Master here. Lets’ check that we understand how sound is produced and what it is. Sound is a form of Energy ( see Science Master Special).  It is transmitted by particles hitting each other.

So what do you think? Could you hear the sound underwater?  Could you hear the sound further along the metal tube?

Lets improve the experiment by making it fairer. How could we do this?

Let us look at the particle arrangement in the air, water and metal.

The average distance between particles for a gas is 4 nanometers (1 nanometer = 10-9 meters), for a liquid it is 0.2 of a nanometer and for the solid 0.0002 of a nanometer.

So. If the first line of particles in the gas starts moving it has to travel 4 nanometers before it hits the second row. For the liquid this would be a smaller distance and for the metal it would be hardly any distance. What does that tell you about the speed of travel of sound?

Does your experiments support your thoughts? Maybe it needs to be modified? How could you modify it to really test your thoughts.

Just a thought of my own. The sound source (drum, spoon tapping, violin) gives the particles around it ENERGY. Those particles in air have to travel a long distance before they hit another particle and pass the sound on. All this time they are losing ENERGY. For the metal the particles only have to travel a little way before passing on the vibration.