Chapter 6 – Action and Reaction Newton’s Third Law Chapter 6 – Action and Reaction

Forces and Interactions Forces involve interactions between one thing and another. So forces always come in pairs—the action force and the reaction force. Newton’s third law: Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. Writing this as an equation: 𝐹 12 =− 𝐹 21 where 𝐹 12 is the force object 1 exerts on object 2 and 𝐹 21 is the force object 2 exerts on object 1.

Newton’s Third Law in Action EVA video Third Law Video

Summary of Newton’s Laws First Law (Inertia) Every object continues in a state of rest or of motion in a straight line at a constant speed, unless it is compelled to change that state by forces exerted on it. Second Law (𝐹=𝑚𝑎) The acceleration produced by a net force on an object is directly proportional to the magnitude of the net force, is in the same direction as the net force, and is inversely proportional to the mass of an object. 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛= 𝑛𝑒𝑡 𝑓𝑜𝑟𝑐𝑒 𝑚𝑎𝑠𝑠 or 𝑎= 𝐹 𝑚 Third Law (Action-Reaction) Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. 𝐹 12 =− 𝐹 21