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Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 1st Law: More Practice Newton’s 2nd Law of Motion: Student Learning Goal The student will be able to state Newton’s 2nd Law and apply it in qualitative and quantitative terms to explain the effect of forces acting on objects. (B3.4) nd 2 Newton’s Law of Motion and Weight Newton’s Second Law of Motion If the net force on an object is not zero, the object will be accelerated in the direction of the net force. Newton’s Second Law of Motion If the net force on an object is not zero, the object will be accelerated in the direction of the net force. Fnet a m Newton’s Second Law of Motion If the net force is not zero, the object will be accelerated in the direction of the net force. Fnet a m i.e. the more massive the object, the harder it is to change its motion (the higher its inertia). Newton’s Second Law of Motion If the net force on an object is not zero, the object will be accelerated in the direction of the net force. Fnet a m Fnet ma Weight The formula F = ma can also be used to calculate the weight Fg of an object Weight The formula F = ma can also be used to calculate the weight Fg of an object, the magnitude of the force of gravity acting on it Weight The formula F = ma can also be used to calculate the weight Fg of an object, the magnitude of the force of gravity acting on it, if the acceleration a is . . . Weight The formula F = ma can also be used to calculate the weight Fg of an object, the magnitude of the force of gravity acting on it, if the acceleration a is the acceleration due to gravity, g = 9.8 m/s2. Fg mg Weight The formula F = ma can also be used to calculate the weight Fg of an object, the magnitude of the force of gravity acting on it, if the acceleration a is the acceleration due to gravity, g = 9.8 m/s2. Fg mg (mass is measured in kg) Weight Fg mg Weight is therefore measured in Newtons. And the direction of the force is always [down]. Weight: Example What is the weight of a 140 kg person? Weight: Example What is the weight of a 140 kg person? Givens : m 140 kg g 9.8 sm2 Unknown : Fg ? Weight: Example What is the weight of a 140 kg person? Givens : m 140 kg g 9.8 sm2 Unknown : Fg ? Select : Fg mg Solve : Fg 140 kg 9.8 sm2 1372 N