Principles of Force

Definition of Force

Force is a push or pull that causes an object to move, change direction, slow down or speed up.
It is measured in Newtons (N).
Mechanics is the branch of physics that studies force and its effects on bodies.

Gravity: The force that attracts a body towards the centre of the earth (weight).
Frictional force: This force opposes movement and can influence the speed and direction of an object.
Air resistance: A special type of frictional force that acts against the direction of movement of an object through air.

According to Newton’s First Law, an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction, until acted upon by another force (inertia).
Newton’s Second Law states that the acceleration of an object is directly proportional to the net force exerting on it, and inversely proportional to its mass (F=ma).
Newton’s Third Law states that for every action, there is an equal and opposite reaction.
The principle of Levers states that the longer the lever arm, the less force required to move it.
The Principle of Moments states that the sum of the moments on one side of the pivot must balance the sum of the moments on the other side for the lever to be in equilibrium.

Understanding these principles are key in improving performance and technique in different sports and physical activities.
For instance, understanding how force affects movement can help optimise a sprinter’s start off the blocks or a footballer’s corner kick.
Knowledge of the principle of Levers and Moments can assist an athlete in improving their throwing or jumping technique.