Forces and Newton's Laws
Forces are pushes or pulls that can be either contact forces (objects touching) or non-contact forces (acting at a distance like gravity or magnetism). Forces are measured in newtons (N), where 1N is the force needed to accelerate 1kg at 1 m/s².
Newton's First Law, also called the Law of Inertia, states that objects resist changes to their motion. An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an unbalanced force. The resistance to change is called inertia and is directly related to an object's mass.
Newton's Second Law explains that force equals mass times acceleration F=ma. This means the greater the force applied to an object, the greater its acceleration. However, the same force applied to objects with different masses will produce different accelerations - more massive objects accelerate less.
Quick Tip: When solving force problems in two dimensions, remember to break forces into their x and y components. The net force in each direction determines the acceleration in that direction!
Newton's Third Law states that for every action, there's an equal and opposite reaction. When you push on a wall, the wall pushes back on you with equal force. This explains phenomena like recoil when firing a gun or jumping from a boat.