Forces and the Laws of Motion Newtons Second

Forces and the Laws of Motion Newton’s Second and Third Laws

Newton’s Second Law ► Force is proportional mass and acceleration § More massive objects require more force to accelerate ► Newton’s Second Law – The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the object’s mass

Newton’s Second Law ► Net external force = mass x acceleration § ΣF = m a § ΣF is the vector sum of all of the forces acting on an object § m is the mass of the object § a is the acceleration of the object ► Often easier to break force and acceleration down into x and y components and then use Pythagorean theorem and inverse tangent to find net force and direction

Newton’s Third Law ► Forces, including field forces, always exist in pairs § When you apply force to an object, the object returns that force to you ► Newton’s Third Law – If two objects interact, the magnitude of the force exerted on object 1 by object 2 is equal to the magnitude of the force simultaneously exerted on object 2 by object 1, and those two forces are opposite in direction

Newton’s Third Law ► For every action force there is an equal and opposite reaction force ► Action-reaction pair – a pair of simultaneous equal but opposite forces resulting from the interaction of two objects ► Action and reaction forces act on different objects, but involve the same two objects

Newton’s Third Law