Here's why:

* Newton's Laws of Motion: Newton's laws describe how forces affect motion:

* First Law (Inertia): An object at rest stays at rest, and an object in motion stays in motion at a constant speed and direction unless acted upon by a net force.

* Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).

* Third Law: For every action, there is an equal and opposite reaction.

* Types of Forces: There are many types of forces, including:

* Gravity: The force of attraction between objects with mass.

* Friction: A force that opposes motion between two surfaces in contact.

* Normal Force: The force exerted by a surface on an object in contact with it, acting perpendicular to the surface.

* Applied Force: A force exerted on an object by a person or another object.

* Tension: The force transmitted through a string, rope, cable, or similar object when it is pulled tight.

In essence, forces cause objects to accelerate, which means they change their speed or direction of motion.