A Simple Slice of Science – What makes the wind?

A Simple Slice of Science – What makes the wind?

This week Dr. Simple answers a question that comes in from a lovely little girl who can sometimes be found here; she would like to know…

What makes the wind?




Did you like Dr. Simple’s explanation or did you find it “a load of hot air“?

Personally I preferred the little girl’s own explanation… she reckons the wind is made by the trees flapping their leaves! A much more simple, and beautiful, explanation, don’t you think?

Remember to keep your questions coming, just leave them in the comments below and Dr, Simple will be happy to answer!

#FunFriday – exploring Magnets

#FunFriday – exploring Magnets

What is a Magnet?


A magnet is an object that can produce a magnetic force around it called a “magnetic field”.  Magnets attract certain types of metals such as iron, nickel and cobalt.


Let’s learn more!


A magnetic field is not visible to the human eye, however iron filings can be used to show the pattern of a magnetic field. The magnetic field around all magnets is strongest at it‛s ends – these ends are called the Poles. One end is called the North Pole and the other is called the South Pole, just like the Earth.

If you put the poles of two magnets together they will either pull together (attract) or push apart (repel); Different poles attract (North and South), similar poles repel!

photo credit: daynoir via photopin cc
photo credit: daynoir via photopin cc

Did you know… small iron rocks on the Earth‛s surface are often natural magnets and these are called Lodestones.

The Earth as a magnet


The Earth is one big magnet – it‛s magnetic field is created by the iron that is in the core of the Earth. The Earth‛s magnetic field is strongest at the North Pole and the South Pole.

photo credit: *~Dawn~* via photopin cc
photo credit: *~Dawn~* via photopin cc
Did you know… many objects is space are magnetic including the Sun!

photo credit: Najwa Marafie - Free Photographer via photopin cc
photo credit: Najwa Marafie – Free Photographer via photopin cc


Did you know… the Earth‛s magnetic field deflects charged particles that come from the sun (Solar Wind) and this creates the wonderful lights called AURORA that can sometimes be seen in the sky.

Magnetic compasses use the Earth‛s magnetic field to determine North, South East and West.




An electromagnet is a magnet that is produced when an electric current is passed around a piece of iron.  Unlike true magnets, electromagnets are only magnetic while the electric current is switched on!

Did you know… the first person to notice that electric currents produce magnetism was a Danish scientist called Hans Christian Oersted, in 1820.
Some countries have started to use high speed trains called “MagLev” trains that are operated by powerful electromagnets.
photo credit: Erwyn van der Meer via photopin cc
photo credit: Erwyn van der Meer via photopin cc


These wheel less trains float on magnetic tracks and can reach speeds of more than 500 km/h.

Two experiments to try at home:

Make a compass:

You will need… a circle of paper, a needle, a magnet and a bowl of water.
What to do… thread the needle through the circle of paper so that nearly all the needle lies on one side of the paper (see below). Stroke the needle 30 times in one direction with one end of a strong magnet.  Lift the magnet between strokes. Float the circle of paper on top of the water in the bowl (needle side up).  The paper should spin around slowly for a few moments and then stop.  The needle should now be pointing North-South.  You can confirm this with a compass if you wish!
So what is happening? The needle contains little particles of iron that are all jumbled up.  When the needle is stroked with the magnet it makes all the iron particles align in the same direction (North-South); the needle is temporarily magnetised!

Make an electromagnet:

You will need.. 1 metre of thin insulated wire, a large iron nail, blue tac, a 1.5 volt battery, paper clips;
What to do… wind the insulated wire tightly around the nail at least 30 times then ask an adult to strip back the insulation from both ends of the wire, exposing about 2 cm of the wire beneath.  Using the blue tac stick one end of the wire to the + side of the battery and the other end to the – end.  Now see if your electromagnet can pick up some paperclips.  If you disconnect the batter the paperclips should fall!!
photo credit: Steve Wilhelm via photopin cc
photo credit: Steve Wilhelm via photopin cc



So what is happening? When the wire is attached to the battery it creates an electric current that runs through the wire, temporarily magnetising the iron particles in the nail. When the battery is disconnected the nail no longer acts as a magnet!


Hope you have fun with these this weekend!  If you have a question or something to add please drop me a note in the comments below!

All in a spin – why does the earth spin

Phew, I really need to wake up alert these days… barely had a sip of tea in me this morning when I got bombarded with lots of questions; I was glad to see that the back of the box of Kelloggs multigrain shapes has lots of fun information about the Stars, Sun, Earth and Moon! (Well done Kelloggs!)  …but this lead to the question…..

photo credit: NASA Goddard Photo and Video via photopin cc


The earth spins because of intertia…. the tendency of a body of mass to remain in it’s state of motion unless acted upon by another force.  Bit of a mouth-full isn’t it?  What it really means is that an object that is at rest (not moving) will stay that way unless another force or influence changes that…. a stone on the ground will stay in place unless we kick it with our foot!  Likewise a moving object will stay moving unless a force acts on it to stop it!  Moving objects on earth stop moving due to friction (think of stopping your bike when you pull the brakes!).

How was the Earth made?

So how does all this relate to the Earth?  Well the Earth is formed from a pile of moving gas and dust created during the big bang! As these gases and particles collapsed under their own gravity they started to spin.  These spinning dust clouds continues to collapse until they formed planets – such as the Earth.  As the planets formed they kept spinning and, in the absence of a significant force to stop them, they continue to do so!

And that is why the Earth spins!

How fast does the Earth spin?

The Earth takes just under 24 hours to make one complete revolution – 23 hours 56 minutes and 0.4091 seconds to be exact. This is called the sidereal period (the length of time a body will make one complete orbit relative to the stars).  So what is the speed of the Earth in kilometres per hour (kph)?  It all depends of where you are standing!  If you were standing at the North or South pole, for example, the Earth would be moving very slowly!  If you were standing on the equator the speed of the earth will be moving at its fastest… that is to say, the circumference of the Earth is greatest at the equator and therefore must move faster to complete one revolution within a day!  To better understand this try holding your finger on a point on a globe while you slowly spin the globe!

Now for the maths…. the circumference of the Earth at the equator is approximately 40,000 km.  If we divide this by 24 (the approximate number of hours in a day) we get 1,667 kph (approx 1000 mph).

The Earth orbits the Sun at a speed of approximately 108,000 kph (67,000 mph).

Do all the planets spin?

Yes they do but not in the same direction or at the same speed.  The inner planets of Solar System (Mercury, Venus, Earth and Mars) spin at a slower speed than the outer, larger planets ( Jupiter, Saturn,Uranus and Neptune).  They all spin in a counter clockwise direction – as viewed from the top (or in a west to east direction), except for Venus and Uranus.  The reason for this is thought to be the result of a significant collision during the formation of these planets .

What about stars?

Stars spin too.  The Sun is a giant star at the centre of our solar system and it rotates on it’s axis, taking 25 days to make a complete revolution!

Image source: NASA

Further reading:

The planets (National Geographic)
Solar System Exploration (NASA)