O Level Physics Definitions

T erm De fi nition Measurement A physical quantity that has magnitude but not direction E.g. Mass, Distance, Speed, Energy A physical quantity that has both magnitude and direction E.g. Force, Displacement, Velocity, Acceleration Scalar Quantity Vector Quantity Kinematics Speed Velocity Acceleration Dynamics Newton's 1st Law of Motion Rate of change of distance Rate of change of displacement Rate of change of velocity An object will continue in its state of rest or uniform motion unless a resultant force acts on it When a resultant force acts on an object of constant mass, the object will accelerate and move in the direction of the resultant force. The product of the mass and acceleration of the object is equal to the resultant force Newton's 2nd Law of Motion Mass, Weight & Density Mass Weight Inertia Gravitational Field Amount of matter or substance in a body Amount of gravitational force acting on a body Reluctance of a body to change its state of rest or moticn Region in which a mass experiences a force due to gravitational attraction Gravitational force per unit mass at a point. Mass per unit volume Gravitational Field Strength Density Turning Effect of Forces Moment of a Force The product of the force and the perpendicular distance from the pivot to the line of action of the force When a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot The imaginary point through which the entire weight of an object appears to act for any orientation The ability of an object to return to its original position after it has been tilted slightly Principle of Moments Centre of gravity Stability Pressure Pressure Energy, Work & Power Principle Force exerted/acting per unit area Energy can neither be created nor destroyed. It can only be converted from one form to another or transferred from one body to another, but the total amount of energy remains constant of Conservation of Energy

T erm De fi nition The product of the force on a body and the distance moved by the body in the direction of the force Rate of work done Work Done Power Kinetic Model of Matter The continuous and random motion of smoke particles in air (or pollen grains in water) due to uneven bombardment by air molecules (or water molecules) Brownian Motion Transfer of Thermal Energy Thermal Equilibrium Conduction No net gain or loss of thermal energy between two bodies it contact Process of thermal energy transfer without any fl ow of th material medium (through molecular vibrations) Process of thermal energy transfer by means of bulk monent of the fl uid The continual emission of infrared waves from the surface ofa body, transmitted without the aid of a medium Convection Radiation T emperature Substance which have physical properties that vary continuously with temperature E.g. Resistance, EME, Pressure Points that are of standard degrees of hotness or coldness which are easily obtainable and reproducible T emperatur