Rachitha (8) asked “Which of the following is not a pure substance A.common salt B.sugar C.rain water D.iron

Rachitha, below is a small animation about some pure substances and impure substances.

This animation initially suggests that Sugar, Water and Lemon Juice are pure substances.

 

The word Pure in science has a special meaning. Something is pure if it is only one substance, not a mixture of different substances …….so the sugar, water and lemon juice are considered pure. Lemonade is a mixture of these pure substances so it cannot be considered as pure.

However, it could be argued that the juice of a Lemon is not pure. It has a sharp taste which suggests that it is an acid. It does in fact consist of a MIXTURE of three acids so it is not pure.

A.  SALT is however pure it only contains a substance called Sodium Chloride.

B. SUGAR is pure if in only contains a substance called Sucrose

C. RAIN WATER is pure if it only contains a substance called H2O.

D. IRON is pure if it only contains Iron atoms. (if you add Carbon to the iron you get a mixture called Steel)

Like the juice of Lemons .. if any of the above (A,B,C or D) contain anything else they will not be pure.

“Will the world ever end?” asks Caroline (10)

Caroline. let us look at the possibilities that the team have suggested.

Yes we are destroying our world. Climate change will in the next hundreds of years will  probably make the Earth unlivable for humans. There might be some animals that will survive so life will survive even if we do not.

There are other things that could destroy our world. An asteroid strike killed the dinosaurs and if there is another strike it could kill humanity. It is reckoned that the Sun is about midway through it’s life. It will at some time begin to die BUT this will not happen for billions of years. When it does die the Earth (our planet) will also die.

Amasidda (?) asked “Give one reason to prove that light is form of energy”

 

Then Amasidda you might be able to answer the question yourself.  Think about what all forms of energy – electric (electricity), light, heat (thermal), movement (kinetic), nuclear, chemical, sound, gravitational, can do. Can they all in some way do work? Can they all be converted from one from one form of energy to another?

What do you think ‘work’ is? Let me know in the comment box below.

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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Luisa 9 asks “How did the first humans appear?”

Thank you Luisa for your second question.  Here are my friends thoughts about how humans appeared.

Thanks team, Luisa let me add some more details.

My friends are correct, it is thought that the first life appeared millions of years ago. The life that formed was not at all like the animals and plants that we see around today. It was very, very small. So small that we would have needed a microscope to see it.  Over the next thousands of years that life changed (we say it evolved) and it reproduced. Sometimes when it reproduced mistakes were made and bigger forms of life were formed. Eventually a mistake in the reproduction led to the first plant (a moss) being formed.

Over the next thousands of years further mistakes were made and  the first animal was born. From then onwards the evolution of animals and plants continued…….UNTIL …..again many thousands of years ago the first apes evolved. The apes continued to have babies and further mistakes were made …… the baby apes walked upright, their brains were bigger, they had less hair, all small changes but over thousands of years small changes can become big changes. The result was that humans were formed and you, me and everybody else are the result.

Things haven’t stopped ….changes (evolution) continues …..we might be very different in many thousands of years time.

Hope this helps. Not happy about something, then ask another question.

How we can take care of the world? asks Luisa (9)

Luisa, an important question. Thank you for asking it. There are obviously some very important things that every human in our world should think about. Let me present you with three of my thoughts. I will let my team present them…….

During the 5 billion years that life has survived on our world a lot of different animals, insects or plants have come to dominate life on our world and not survived.  One of the early plants that became dominant was a type  of moss. It grew so much that it poisoned the atmosphere with all the oxygen that it produced. Dinosaurs were destroyed when our world (the Earth) was hit by an asteroid, it created so much dust that the plant life they eat stopped growing.

Life survives but in a different forms. We should be careful because we might be the next form of life to disappear. 

Unknown (age 7) asked – “Why is the sky blue?”

Hello unknown. I would not normally answer questions to an unknown questioner, but, as it it such an interesting question I asked my friends for some comments.

You are right. Where does the colour come from? It was in 1671 that the famous scientist, Newton, discovered that white light was a mixture of different coloured lights. He did this by passing white light (the light from the Sun) through a glass prism. Look at what he got……….

Later it was found that some of the blue light in the Sun’s light had difficulty passing through the Earth’s atmosphere. this blue light was scattered as it passed through the atmosphere therefore giving the sky a blue colour.

Some of the blue light still got through and appears as part of the white light in the prism experiment and also in the rainbow. In the rainbow the drops of rainwater act as small prisms.

Hope this makes sense. if you want to give your name please let me know in the comment box.

(amended 21/9/18 – raindrops as prisms added)

“What does “eco” in ecosystem mean?” asks Austin (8)

I will just add a few words myself. Thanks for your input.

I like the idea of an ant’s nest being an example of an ecosystem. The nest is ‘everything’ it’s a home, a place to live and to work from, a creche for baby ants, a food store, a food production place, a protective environment, maybe an ant hospital, and lot’s more. It is an ecosystem.

The word ‘eco’ also combines with ‘logy to form ‘ecology’. This is like the word ‘bio’ combining with ‘logy’ to form ‘biology’.  The word ‘logy’ is a word which originally described lots of learning.

I will stop now. For an eight year old I think everything gets very complicated. I very much like the ant’s nest described as an ecosystem.Maybe you could let me know of other ecosystems?

STOP

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

Thank you for your question Damian. I asked my friends about it and they had the following thoughts.


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