Wow!
That is amazing! Wow! It's by magic!
If I've got this right, I should be able to balance
this on top of this. Let's have a go.
Wonderful.
I can even give a nudge and it remains completely balanced.
However, I take this sweet off and eat it,
it goes all horribly wrong.
Making sculptures like this
is a great fun activity to do with your children and it can also provide them
with an opportunity to investigate
balance and stability.
Right girls, here's a challenge:
See this piece of carrot? I want to see if you can balance this carrot on this stick
on top of the bottles. Can you balance it?
No!
Then try this one.
Doesn't really work too well, does it? Why don't you think it's working?
Um, it's a bit bumpy?
So what about trying to poke the stick into the carrot at some point?
Be careful because the pointy end is a bit sharp.
It's exactly the same really. It's not helping.
Here's one that we made a little bit earlier.
Shall we have a go and see if this balances? Okay!
It's the same carrot, same stick with a bit of an uneven end.
Let's see if we can balance it.
Aha! Do you want to have a go, see if you can make one like that?
Wow! Hooray!
Hooray! One, two...
Yay! It's by magic isn't it! But how can they do it?
Is it because of the weight?
And where is the weight? Is it at the bottom or the top?
At the bottom and the top.
Look at this!
That is amazing! How many are there!?
One two three four...
When you have an object like a pencil,
and try to balance it on your finger, it balances when it's roughly in the middle.
This point is called the centre of mass, or the centre of gravity.
You can think of it as the point at which
the mass or weight of an object is evenly distributed.
For this pencil, you can see
that it is approximately in the middle. Oops!
But for some objects, like a hammer,
obviously a hammer is much heavier at one end then the other,
so if you try to do it in the middle there's no way it would work,
so the centre of mass is much nearer
the heavier end. I find this quite tricky because I've got small fingers!
But for an object like this roll of masking tape
the weird thing is that the center
of mass is not within the object itself.
That seems a bit weird doesn't it?
But if I put my finger under here you can see it roles off
very easily. That's because center of gravity is right in the middle of the
object and it's hard to get it directly above my finger.
It wants to roll off either way. But if I put my finger here,
as you all know from experience, dead easy to balance it!
The centre of gravity is right here, underneath.
That's the secret to making a successful
balancing sculpture. To make sure the centre of mass
is underneath the point at which is being balanced
on the object.
If it's tipping over to this side a bit too much, what do you think you might need to do?
The balloon's lighter than the sweet!
You can change the centre of mass of a balancing sculpture
by adjusting the position of the various
bits and pieces we put together to make it.
That's really good, sweetheart!
Wow, look, it balances!
Well done, darling, that's amazing!
Understanding the science of stability and how things balance
is important for lots of things like designing a building or making a sports car.
Obviously today we haven't done anything quite as complicated as that,
but these sculptures are a fantastic way
to start your children thinking about some of those concepts.