The fundamental principle that governs acceleration is Newton's Second Law of Motion. It states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In simpler terms:

Force = Mass x Acceleration

This means:

* Force causes acceleration: A force applied to an object will cause it to accelerate. The larger the force, the greater the acceleration.

* Mass resists acceleration: The more massive an object is, the harder it is to accelerate.

Here are some examples of forces that cause acceleration:

* Gravitational force: This is the force that pulls objects towards each other, like the Earth pulling you towards its center. This force causes objects to accelerate downwards when they fall.

* Friction: This force opposes motion between surfaces in contact. It can slow down or stop objects from moving. For example, friction between your shoes and the ground helps you accelerate when you walk.

* Applied force: This is a force that is directly applied to an object. For example, pushing a box across the floor or pulling a wagon with a rope applies a force that causes acceleration.

* Electromagnetic force: This force is responsible for interactions between electrically charged objects. It can cause objects to accelerate, like a magnet pulling a piece of iron.

In summary, any force acting on an object will cause it to accelerate, and the amount of acceleration is determined by the size of the force and the object's mass.