02 Newtonian Mechanics

Big Ideas 1. The study of motion involves first studying an idealised system in which complicating factors (like friction) are absent, and then transferring this understanding to a real physical process. Analysis of the motion of an object is performed using free-body and vector diagrams, graphical analysis as well as mathematical formulae. 2. There are four fundamental forces in nature: gravitational and electromagnetic forces (which are responsible for our everyday experiences) and strong nuclear and weak forces (which operate only at the sub-atomic scale). Gravitational force (a very weak attractive force between two masses) is very long range and is responsible for the interaction between celestial objects in the Universe as well as the Earth’s gravitational pull on us. Electromagnetic force (a very strong force between two charged objects) is very short range and is responsible for all inter-atomic forces of attraction and repulsion e.g. electrostatic forces, contact forces (normal force, friction, fluid resistance) and magnetic forces. 3. When any two bodies in the Universe interact, they can exchange energy. The law of conservation of energy states that in any closed system (including the Universe), the total quantity of energy remains fixed - energy is transferred from one form to another but none is lost or gained. Many forms of energy can be considered to be either kinetic (motion) energy or potential (stored) energy.4. Newton’s three laws of motion and his law of universal gravitation have been successfully applied to explain and predict motion of terrestrial and celestial objects. Newton’s laws further show that it is possible to express natural phenomena in terms of a few special rules or laws that can be expressed in mathematical formulae. 5. When any two bodies in the Universe interact, they can exchange momentum. The law of conservation of momentum states that in any closed system (including the Universe) the total quantity of momentum is invariant - momentum can be transferred from one body to another (by an impulse) but none is lost or gained. 6. Many kinds of motion in nature are periodic motions or oscillations. The ideas from a type of oscillation known as simple harmonic motion is applied to explain many physical situations such as waves, sound, alternating electric currents and light.