Here's why:
* Newton's First Law of Motion (Inertia): An object at rest stays at rest, and an object in motion stays in motion at a constant velocity unless acted upon by a net force.
* Newton's Second Law of Motion: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This means:
* Acceleration: A net force causes an object to accelerate, which means its velocity changes.
* Zero net force: If the net force is zero, the object will not accelerate, and its velocity will remain constant.
In simpler terms:
* To start moving something: You need a force to overcome its inertia and make it accelerate.
* To stop something moving: You need a force to slow it down and eventually bring it to rest.
* To change the direction of something moving: You need a force to push or pull it in a different direction.
Therefore, any force that results in a net force acting on an object will change its velocity.
