Further Mechanics: Force

Further Mechanics: Force

Basic Concepts

• Force is a vector quantity characterised by both magnitude and direction.
• It is measured in Newton (N) in the International System of Units (SI).
• Forces can cause an object to accelerate, slow down, remain in place, or change direction.

Action and Reaction Forces

• Every action has an equal and opposite reaction according to Newton’s third law. These forces always come in pairs and involve different objects.
• Action and reaction forces are equal in magnitude but opposite in direction.

Types of Forces

• Gravitational force: The pull that the Earth exerts on an object.
• Frictional force: The resistance that one surface or object encounters when moving over another.
• Tension force: The pulling force transmitted along a string, rope, cable or similar object.
• Normal force: The force exerted by a flat surface which supports the weight of an object resting on it.

Newton’s First Law

• Newton’s first law, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity, unless acted upon by a net force.

Newton’s Second Law

• Newton’s second law states that the acceleration of an object is directly proportional to the net force acting on it, and inversely proportional to its mass. This can be shown by the equation F = ma.

Free-Body Diagrams

• Free-body diagrams are graphical illustrations used to visualize the forces acting on an object. The size of the arrow represents the magnitude of the force and the direction of the arrow indicates the direction of the force.
• When analyzing these diagrams, it’s crucial to find the resultant force and establish whether the forces are balanced or unbalanced.