Newton's Second Law as a Guide to Thinking One Newton is defined as the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. The definition of the standard metric unit of force is stated by the above equation. By substituting standard metric units for force, mass, and acceleration into the above equation, the following unit equivalency can be written. If necessary, review this principle by returning to the practice questions in Lesson 2.Ĭonsistent with the above equation, a unit of force is equal to a unit of mass times a unit of acceleration. If all the individual forces acting upon an object are known, then the net force can be determined. As discussed in an earlier lesson, the net force is the vector sum of all the forces. It is the net force that is related to acceleration. Do not use the value of merely "any 'ole force" in the above equation. It is important to remember this distinction. The acceleration is directly proportional to the net force the net force equals mass times acceleration the acceleration in the same direction as the net force an acceleration is produced by a net force. In this entire discussion, the emphasis has been on the net force. The net force is equated to the product of the mass times the acceleration. The above equation is often rearranged to a more familiar form as shown below. This verbal statement can be expressed in equation form as follows: a = F net / m Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. As the mass of an object is increased, the acceleration of the object is decreased. As the force acting upon an object is increased, the acceleration of the object is increased. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object. The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. Newton's second law of motion pertains to the behavior of objects for which all existing forces are not balanced. The presence of an unbalanced force will accelerate an object - changing its speed, its direction, or both its speed and direction. According to Newton, an object will only accelerate if there is a net or unbalanced force acting upon it. Objects at equilibrium (the condition in which all forces balance) will not accelerate. The first law - sometimes referred to as the law of inertia - states that if the forces acting upon an object are balanced, then the acceleration of that object will be 0 m/s/s. Of the main group elements, fluorine has the highest electronegativity (EN \(= 4.0\)) and cesium the lowest (EN \(= 0.79\)).Newton's first law of motion predicts the behavior of objects for which all existing forces are balanced. Electronegativities generally decrease from top to bottom within a group, due to the larger atomic size. Note that there is little variation among the transition metals. Because most noble gases do not form compounds, they do not have electronegativities. Alkali metals have the lowest electronegativities, while halogens have the highest. This is due to an increase in nuclear charge. The electronegativities of nonmetals are generally high.Įlectronegativities generally increase from left to right across a period. Nonmetals have more valence electrons and increase their stability by gaining electrons to become anions. Consequently, the electronegativities of metals are generally low. Since metals have few valence electrons, they tend to increase their stability by losing electrons to become cations. (Credit: Christopher Auyeung Source: CK-12 Foundation License: CC BY-NC 3.0(opens in new window)) The largest electronegativity (3.98) is assigned to fluorine and all other electronegativity measurements are on a relative scale. \): The electronegativity scale was developed by Nobel Prize winning American chemist Linus Pauling.
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