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

Jaydeep. An interesting question, which I need to think about. I suspect it might be a question of ‘testing’. How did you arrive at the question? Did it include elements of ‘fair testing’? I shall start by passing it over to my friends.

Thanks team. Yes, I agree, science knowledge is based upon fair testing. Jaydeep’s question suggest that he has evidence that sponges absorb more hot water than cold. It is and interesting thought BUT is it true? That’s what a scientist would ask.

What do I think? My initial thought is that as water gets hot it expands, so…., the sponge might absorb less water. From another viewpoint it might be argued that the hot water ‘warms up’ the sponge and causes the sponge to expand, thus absorbing more water. Another argument might be that because both the water and the sponge expand when they get hot …..things cancel out.

The important point is that if the original investigation was not fair all the arguments about Why are meaningless.

Jaydeep ….do a fair test`and then ask the question. Many thanks for an interesting input.

If pressure on a gas is increased what will happen inter-particle force?” asks Prince (13)

Prince.  An initial answer. You have to think of how you are going to increase the pressure of a gas. I can think of two methods …..imagine a gas in a Coke tin. The gas particles ar rapidly moving around, bouncing of each other and the sides of the container. We can increase the pressure by (1) decreasing the volume of the coke can ….the particles therefore will hit the sides more often (increasing pressure) or (2) increasing the amount of gas in the can which again increases the number of gas particles that hit the side of the can, again increasing pressure. In both these cases the intermolecular forces are quite small. Most gas particles are fairly inert , they have inter molecular forces but they are slight. Water (H2O) and NH3 (ammonia) are probably exceptional. HOWEVER as you increase the pressure further the gas molecules have less room to move and they get closer to each other …the intermolecular forces increase UNTIL they are so strong, because there are so many molecules in the small space that the gas becomes a LIQUID. This is helped if you reduce the temperature at the same time (molecular movement is temperature dependant).

 

Sorry a  big explanation …will tidy up in due course.

 

 

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

http://en.wikipedia.org/wiki/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.

Destiny (10) asks “Did/are unicorns real?”

Destiny, thanks for this second question. Interestingly it has connections to your previous question about evolution.

I asked my friends about unicorns.

The fact that there are no fossils does not mean that unicorns never existed. If you look at how modern humans evolved from apes there are a lot of gaps in our understanding, which could be linked to fossils that have not yet been found.

Where fossils have been found we can get lots and lots of information from them especially from the age of the rock in which they are found. This is to do with something called radioactive decay. This allows the fossils to be placed fairly accurately on the ‘evolution table’.

I have two immediate thoughts about unicorns. Firstly they are completely made up and secondly they are a brief part of an evolutionary story that didn’t survive. For example an animal (horse, deer, goat or other animal) was born with one horn by some biological accident, it lived but it’s children were ‘normal’ so the trait ended.

I prefer the mythical, made up model. I would like your thoughts.

“Did humans evolve from monkeys?!?!” asks Destiny (10)

A great question Destiny and a difficult one to answer. You use the word ‘evolve’ in your question. I think we should spend the first part of a possible answer looking at that word – ‘evolve’. I thought I would ask my friends about this. Let’s see what they come up with ….

It was Darwin, a famous scientist, who proposed that all living things over time are slowly evolving. So another thing we have to think about is time. 

Life on our planet is thought to have been created four and a half billion years ago. That is 4,500,000,000 years ago. That give a lot of time for something to happen (evolve)  gradually.

Scientist think that ALL living things on our planet started 4.0 billion years ago with the formation of the first micro-organism that could reproduce itself. It was no bigger than a pinhead.

Below is a crude timeline which illustrates  how different life forms evolved (developed) over those millions and millions of years from that pinhead.


So Destiny, we have evolved from the primates but the primates evolved from other living things, and it started 4.0 billion years ago from that pinhead

I think the crucial factor in understanding this in the time span …which is unbelievable to us who live for such a short part of the story.

Unhappy about this, then please write a comment or ask another question.

(rewritten June 5th 2018 )

Chris (10) asks “How can you correctly determine the age of a tortoise or turtle?”

Chris thank you for your question. Some people suggest that it is the number of scutes (the bony rings that the tortoise has on its shell. However look at this baby tortoise breaking out of it’s shell.

Here he/she is and already there is more than one scute. Maybe we need to take a hint from a tree. How do you find the age of a tree. When you cut a tree down you can see inside of the bark a series of rings. (You can obviously do this without chopping the tree down).  Look at the image below.

The scutes of a tortoise also have rings. The image below is an ‘old’ tortoise.

This image is of a very young tortoise

Maybe these will give you a clue about the tortoises age. It is thought that this could be a rough age indicator.

Alternatively you could get a size chart, however, like the rings it is difficult to accurately determine the age of a tortoise. Maybe the only true way is to know when it was born.

“Is time travel possible ?” asks Lachie (9)

Thanks for the question Lachie . My friend is correct, Albert Einstein thought that time travel would be possible because of something he called relativity. It seems to be about the time it takes to move through a given distance (space) and the speed of light. The faster you go the slower the time that has past. That is a very, very difficult idea to understand. Even I find it difficult ….. but lets try and give you an example

Suppose you could move through space at or around or about 186,000 miles per second, which is the speed at which light travels?

Say you were 9 years old when you left Earth in a spacecraft traveling at about the speed of light (which is much faster than we can achieve now), and celebrated only five birthdays during your space voyage. When you get home at the age of 14, you would find that all your classmates were 59 years old, retired, and enjoying their grandchildren! Because time passed more slowly for you, you will have experienced only five years of life, while your classmates will have experienced a full 50 years.

So, if your journey began today in 2018, it would have taken you only 5 years to travel to the year 2068, whereas it would have taken all of your friends 50 years. In a sense, this means you have been time traveling.

According to Einstein’s ideas you can only move forward in time you cannot move backwards. However we do not at the present time have any vehicle that could reach the speed of light so if you want to travel in time you might have to wait a little while.
(revised 23rd May 2018)

Tiago (?) asked “Why are beach sands so different in colour and size?”

I asked my friends about this but they were more interested in investigating sandcastles than trying to answer the question.

It most certainly is something to do with the water. Water wet’s most things.There are some things that water doesn’t wet. Things which are wetted by water are called hydrophilic while those that are not wetted by water are called hydrophobic.

Sand is hydrophilic so water can act as a sort of glue between sand particles, holding them together. It’s not a very strong ‘glue’ but it is enough to stop the sand particles falling apart in the sand castle. For more on this look at this previous question. Some scientist have done some research and found that you need between 1% of the mixture to be water to keep the sand together. T

There is, however, the small problem of the type of sand. There are lots of different types of sand. Sand comes from broken rocks and animal skeletons. Different rocks and skeletons change the colour of the sand. The most common sand is from quartz rock (SiO2) 

Black sand comes from eroded volcanic material such as lava, basalt rocks, and other coloured rocks and minerals, white sand was once the skeleton of animals, shells or coral reefs.

Sand is formed by the action of the sea on the rocks, constantly moving the rocks and breaking them. It is thought that the flatter the beach the smaller the particles of sand are. For steep beaches the sand particles are larger. It is something to do with wave motion.

“How, where or when we’re magnets found or made?” asks Sam (11)

Thanks for the question Sam. Magnets and magnetism was first discovered about  9000 years ago. A long time ago. It was found in rocks and called ‘lodestone’. Lodestone is a naturally occurring compound of iron. It is thought that it was magnetised by lightning strikes.

We will make our own magnets by using a slightly weaker form of electricity.  Here are my team.

Firstly let us try to make a magnet (without using lightning)

You will need a battery and a length of wire and some paperclips. The a collection of nails. Try and find as many different nails as you can. Wrap the wire around the nail and sellotape the bare wire ends to the terminals of the battery. See the diagram below. See how many paperclips you can pick up? Are some nails better than others?

DO NOT USE MAINS ELECTRICITY. IT IS VERY DANGEROUS. 

You might have found out that only certain metals can be made into magnets. These metals are called ferromagnetic metals.

Included in this group are the metal iron and the alloys of iron with the metals cobalt, nickel.

It is thought that in these metals (including iron) have some electrons called ‘free electrons’ (not sure what an electron is, then go to Science Master Special – Atoms and Atomic Structure). It is these ‘free electrons’ that are involved in magnetism. In the alloys the  ‘free’ electrons align themselves with the magnetism of the external magnet, making a (for the alloys) a permanent magnet.

Look at the short video I have made below. In the ferromagnetic metal (iron alloy) crystal domains you will see free electrons. In the metal these will be moving freely. As they begin to interact with the external magnetic field, they begin to align themselves, making a permanent magnet.