Moments and center of gravity | strip-header-layout

Chapter 5 Moments and Center of Gravity:

If someone tries to close a door near the hinges it will require a huge force to close it, however if you close it near the door handle only a small force will be required. This proves that the smaller force has as big a turning force as the smaller turning force depending on where you close it from
The point or line about which the door turns or rotates is called the fulcrum. In the case of the door the line through the hinges is the fulcrum

1. By increasing the size of the force itself

2. By increasing the distance from the applied force to the fulcrum

The measure of the turning effect of a force is called the moment
Moment of a force: (Force) x (Perpendicular distance from the force to the fulcrum)

A lever is any rigid body that is free to turn or rotate about a fixed point called the fulcrum
The Law of the Lever: When a lever is balanced by any number of forces the sum of the clockwise moments acting on it is equal to the sum of the anti-clockwise moments.
For example if a mom and her son are on a see-saw and the boy weighs 400n and is 2 meters from the center or the fulcrum and his mother weighs 500n and is 1.6 meters from the fulcrum. This see-saw is balanced as the clokwise moments are equal to the anti-clockwise moments.

The center of gravity of an object is the point through which all the weight of the object appears to act
Equilibrium: An object that is balanced is said to be in equilibrium
Stable Equilibrium: The fulcrum is above the center of gravity if it is moved, the center of gravity rises but gravity soon pulls it back to its lowest position again i.e. Center of gravity returns to original position
Unstable Equilibrium: The fulcrum is below the center of gravity. If this center of gravity is moved it will not return to its original position. Its center of gravity falls when pulled when pushed to one side, gravity then just keep pulling it down
Neutral Equilibrium: The fulcrum is at its center of gravity. If this center of gravity is moved it will just stay in its new postioion. The center of gravity does not rise or fall

When designing anything that can topple the golden rule is: "A body will topple when a verticle line through its center of gravity falls outside its base"
A low center of gravity helps stability. For example, a low center of gravity helps stabilize a double decker bus
These buses are designed to stay upright even if they tilt because their center of gravity is so low. This is because the designers put the heavier parts such as the engine at the lowest point
Another way of making a body more stable is to make its base wide.