# Talk

## How do i explain E=Mc^2 to a 9 year old?

(14 Posts)
PavlovtheCat Wed 28-Oct-15 09:27:43

I know it's the amount of energy produced by a specific amount of mass. But, I sort of know what it means, but not how to explain it. At all, let alone to a 9 year old

maths is not my strong point

megletthesecond Wed 28-Oct-15 09:31:02

I'd like to know too.

Have dick 'n' dom covered it in Genius?

penny13610 Wed 28-Oct-15 09:32:20

How long does it take for light to get from the sun to us.
Then use someones elses explanation.

megletthesecond Wed 28-Oct-15 09:35:21

Can it be done with Lego ?

honeysucklejasmine Wed 28-Oct-15 09:37:52

Why on earth would you want to do that? Is it something they have asked about? Clever child!

Agree they need to understand the meaning if each term and how it came about, before looking at the equation as a whole.

multivac Wed 28-Oct-15 09:42:12
CoteDAzur Wed 28-Oct-15 09:42:43

Mass and Energy are convertible into each other, just like water can be boiled into steam or frozen into ice cubes. Example: Food we eat gets converted into energy in our bodies.

(I know this is a huge oversimplification and the analogies don't hold 100% but it's what a 10-yr-old understands)

That will get you talking about the speed of light: It is constant in space (although it is different in air and water for example, which is why you see objects at the bottom of the pool slightly away from where they actually are - called 'refraction').

CoteDAzur Wed 28-Oct-15 09:49:36

DD read a picture book for children about the life of Albert Einstein, where Theory of Relativity was also briefly explained with moving trains and bouncing balls (as Einstein explained in his time).

There are quite a few videos on YouTube that explain the concept of "relative motion" and why time slows down as you approach the speed of light, with the same train example.

PavlovtheCat Wed 28-Oct-15 09:53:24

honey not as clever as it sounds. Although if she grasps it I will be impressed. There is a show called Mc2 and I saw some toys advertised for it. I asked her is she liked the tv series called 'MacTwo' and she sighed and said 'no mum it's M C Squared! you know like in maths?!' and I questioned how it was spelt, showed her the equation as it's meant to be written and she asked what it was and how it was worked out. I sort of went 'er er' mentioned Einstein, energy and mass and she got bored as I wasn't really making sense! So I said I would find a child friendly way to explain it.

PavlovtheCat Wed 28-Oct-15 09:54:59

Thank you all so much. I will start with breaking it down, as mentioned, and will check out some youtube stuff. I'm glad it is as difficult as it sounds to explain

SurlyCue Wed 28-Oct-15 09:56:40

I learned this last year. But i'd need to really think about it to be able to explain it to someone thank heavens for google!

PavlovtheCat Wed 28-Oct-15 10:03:09

we looked at the youtube link, which I understood, but he talked quite fast so we stopped and re-listened to a few sections. Broke it down a bit. She sort go gets it. Will get the book on Einstein that you mentioned Cote.

She recently had a book about Evolution/Darwin & Wallace. She found it boring as it was quite a dry book, so we read bits of it tougher and she enjoyed learning about it. Her teacher said they will learn more about Evolution and Darwin in the next couple of years.

I am guessing that E=MC^2 is too advanced for her to fully grasp now But if she has the seeds planted, it will be easier for her to grasp over the coming year(s).

PavlovtheCat Wed 28-Oct-15 10:03:42

I meant to say, re the Darwin/Wallace book that perhaps it's a similar type of book to the one about Einstein.

The maths of it easier to follow, perhaps, if you do a worked example.

suggest you use MKS

so

i kilogram of matter equals how much energy?

1 times (speed of light expressed in metres per second squared)

which gives you the answer (I think) in Joules.

Then (the internet is your friend) convert joules into Kilowatt hours and google the annual electricity consumption of the UK and see how many years the UK could, in theory run on one kilo.

That sort of thing.

Enjoy!

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