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Wonders of Physics

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Real-life ‘roly-poly toy’ – China

Well, that’s Physics =)

Refer to this post on the concept – Balancing toy


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Important Concepts on Moments

When a system is in equilibrium, 2 conditions are met.

1) Principle of Moment (POM):
Sum of anticlockwise moment = Sum of clockwise moment

2) Net force = 0N; all forces are balanced:
Total downward forces = Total upward forces

Whenever a force passed through the pivot point, that force will not create any moment as there is no perpendicular distance from the force to the pivot. Hence this force will not be included in the calculation of moments.

2014 moments small

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Balancing Toys

Balancing toys always return to its original position as their centre of gravity (CG) are below the pivot (balancing) point. This kind of system will create a restoring moment which helps to return the system to its original position when displaced slightly.


Such systems are in stable equilibrium. Characteristic of such system is that when displaced, the CG rises.