# Forces and Motion: Turning Effects and Centre of Gravity

## Forces and Motion: Turning Effects and Centre of Gravity

• Understanding forces and motion is fundamental in physics. Forces have both direction and magnitude, and can affect the state of motion of an object.
• A force can cause an object to accelerate, slow down, remain in place, or change shape.
• The turning effect of a force is correlated with the size of the force and the distance from the pivot at which the force is applied. This can be calculated by the formula: moment = force x distance from pivot.
• More than one force can act on an object at the same time. The effects of these forces can be added up using the principles of vector addition to find the resultant force.
• A force can produce a turning effect or moment. This happens when a force is applied at a distance from a pivot (the point about which an object may rotate). The larger the distance or the bigger the applied force, the larger the moment.
• An equilibrium is a state in which opposing forces or influences are balanced. If an object is in equilibrium, the total clockwise moment about any point is equal to the total anticlockwise moment.
• The principle of moments states that for a body to be in equilibrium, the sum of the clockwise moments about a pivot must be equal to the sum of anticlockwise moments.
• The centre of gravity of an object is that point through which a single force, or weight, can be said to act.
• The stability of an object is linked with the position of its centre of gravity. Laterally stable objects have a low centre of gravity and a wide base.
• GGCE (general guidelines on calculating equilibrium) can be used to understand more complex scenarios, such as when more than two forces or multiple pivots are involved.