Engineering Physics I Chapter 2: Force and Motion Dr. CHAN, Man Ho Department of Physics
Ch2. Force and Motion 2.1 Newtonian Mechanics 2.2 Newton’s First Law of Motion2.3 Newton’s Second Law of Motion2.4 Newton’s Third Law of Motion2.5 Some Particular Forces 2.6 Applications of Newton’s Laws
2.1 Newtonian Mechanics Three laws of motion (empirical) –basis for classical mechanics Describe the relation between a force and the motion it causes Can be applied to the motion of objects ranging in size from the very small to astronomical. Isaac Newton (1642 –1727)
2.2 Newton’s First Law of Motion
2.2 Newton’s First Law of MotionNewton's first law of motion: all objects resist change in their state of motion. All objects have this tendency, i.e. they have inertia. The mass of an object is a measure of its inertia. Larger mass more inertia larger tendency to resist changes in its state of motion The mass of an object is usually given in unit of g(gram) or kg(kilogram).
2.2 Newton’s First Law of Motion, . non-
2.3 Newton’s Second Law of Motionits
2.3 Newton’s Second Law of MotionDefinition of Force◦According to the modern version of Newton’sSecond Law of Motion, one may express it in equation form: ◦For deeper understanding of above equation, we rewrite the R.H.S. as: netFmassaccelerationmad mvdvdpmamdtdtdt
2.3 Newton’s Second Law of MotionDefinition of Force◦.
2.3 Newton’s Second Law of MotionUnit of Force◦
2.3 Newton’s Second Law of MotionNet Force 10 N 10 N 10 N 20 N These forces balance.