4-4-newtons-third-law-of-motion_summary

Newton's Third Law of Motion states that whenever a first object exerts a force on a second object, the first object experiences a force equal in magnitude but opposite in direction to the force that it exerts. This law is also known as the action-reaction principle. It is useful for figuring out which forces are external to a system when setting up a problem. The normal force, tension, and thrust are examples of forces that can be understood with the aid of Newton's Third Law. In everyday examples, such as pushing off the wall while swimming or a car moving forward, we see Newton's Third Law in action, with the action force causing a reaction force that moves the object of interest. When applying Newton’s Third Law, one should consider external forces, such as weight, normal force, tension, and thrust, and solve problems by identifying the system of interest, drawing a free-body diagram, and using Newton's Second Law to find the acceleration or other physical properties.