What you need:
- 12 identical iron nails
- A block of wood
- A hammer
- Adult supervision
What to do:
1. Hammer one nail into the wooden block. It should stand upright on the block.
2. Can you balance the other nails over it?
3. Lay one nail flat on a table or on any even surface.
4. Place the other nails along the horizontal nail’s length with their heads side-by-side as shown in the picture.
5. Lay the last nail over the heads of the others in such a way that its tail faces the head of the first horizontal nail.
6. Carefully, lift up this entire weaving of nails and place it on the head of the upright nail standing on the block of wood.
What happens:
If you try to balance the other nails on the upright nail without the weaving, they all fall over.
But the interwoven nails hold up on the single nail pretty well!
Why?
The ‘Centre of gravity’ is the point inside a body, where all its weight is concentrated. For an evenly-shaped form, like a ball, the centre of gravity lies at its centre. But for odd shapes, like a nail, the centre of gravity is shifted towards the heavier end. For the human body, the centre of gravity changes depending on the position the body is in!
In this case, the interwoven structure of nails becomes stable when its centre of gravity lies at the point resting on the bottom nail. If you have put too many nails to the left or to the right, the centre of gravity shifts to the heavier side causing the structure to topple.
Picture Credit : Google
