What is force? Force is a push or a pull that can cause an object to change. Forces can change an object's motion - making it start moving, stop moving, change speed, or change direction. Forces can also change an object's shape by stretching, compressing, or deforming it.
Newton's First Law of Motion states that an object at rest stays at rest, and an object in motion stays in motion with the same speed and direction, unless acted upon by an external force. This is also known as the Law of Inertia. Without a force acting on it, an object will maintain its current state of motion. A stationary object remains stationary, while a moving object continues moving in a straight line at constant speed.
Newton's Second Law of Motion states that force equals mass times acceleration, written as F equals m times a. This law describes the relationship between an object's mass, the force applied to it, and its acceleration. The greater the mass of an object, the more force is needed to accelerate it. If we apply the same force to objects with different masses, the object with less mass will accelerate more. Conversely, if we want objects of different masses to accelerate at the same rate, we need to apply proportionally more force to the heavier object.
Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. Mathematically, this means that when object A exerts a force on object B, object B simultaneously exerts a force of equal magnitude but in the opposite direction on object A. These action-reaction force pairs are always equal in magnitude, opposite in direction, and act on different objects. This principle explains many everyday phenomena, from how we walk by pushing against the ground, to how rockets propel themselves by pushing exhaust gases backward.
To summarize what we've learned about force: Force is a push or pull that can change an object's motion or shape. Newton's First Law tells us that objects maintain their state of motion unless a force acts on them. Newton's Second Law states that force equals mass times acceleration, expressed as F equals ma. Newton's Third Law states that for every action, there is an equal and opposite reaction. These principles are fundamental to understanding how objects interact in the physical world, from everyday activities to complex engineering and space exploration.