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force : a push or a pull exerted on an object in order to change the motion of the object; force has size & direction. Ch.5, Sec.2 – What Is A Force?. newton : the SI unit for force and weight (N). Forces Acting on Objects.
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force: a push or a pull exerted on an object in order to change the motion of the object; force has size & direction Ch.5, Sec.2 – What Is A Force? • newton: the SI unit for force and weight (N) • Forces Acting on Objects - not all forces can be seen and forces can only act on objects with matter - gravity & magnetism are sometimes hard to see! The Earth’s gravity pulls the atmospheric gases closer to its surface!
Ch.5, Sec.2 – What Is A Force? • Determining Net Force • net force: the combination of all the forces acting on an object - calculating net force is determined by the direction in which the forces are placed - If one person applies 8 N of force to a book and another person applies 6 N of force (inthe same direction), then the book requires 14 N of force to be moved!
Ch.5, Sec.2 – What Is A Force? - If one person applies 20 N of force to a book and another person applies 18 N of force (inthe opposite direction), then the book will have 2 N of force pushing it to the left! - What is the net force of an object when you combine a force of 7 N north with a force of 5 N south? 5 N south 2 N north = 7 N north
Ch.5, Sec.2 – What Is A Force? • Balanced & Unbalanced Forces - net force is important because it tells us whether the forces on an object are balanced or unbalanced - when the net force on an object is 0 N, the forces are balanced! - balanced forces will not cause an object to change its motion - balanced forces will not cause an unmoving object to start moving
Ch.5, Sec.2 – What Is A Force? - when the net force on an object is not 0 N, the forces are unbalanced! - unbalanced forces cause a change in motion, such as speed or velocity - unbalanced forces are necessary to cause an unmoving object to start moving