PURE PHYSICS DEFINITIONS

PURE PHYSICS DEFINITIONS Physical quantity A physical quantity is a quantity that can be measured. It consists of a numerical magnitude and a unit . Period The period of a simple pendulum is the time taken for one complete oscillation . Scalar quantities Scalar quantities are physical quantities that have only magnitude . Vector quantities Vector quantities are physical quantities that have both magnitude and direction . Distance The total length covered by a moving object regardless of the direction of motion. Displacement The distance measured in a straight line in a specified direction. Speed Distance travelled per unit time Velocity Rate of change of displacement Acceleration Rate of change of velocity Uniform acceleration Constant rate of change of velocity Gradient of d-t graph Gives the velocity of the object Gradient of v-t graph Gives the acceleration of the object Area under v-t graph Gives the displacement of the object

Mass Measure of the amount of matter in a body . Weight Gravitational force acting on an object that has mass. Gravitational field A region in which a mass experiences a force due to gravitational attraction. Gravitational field strength, g Gravitational force per unit mass placed at that point. N1L Newton’s First Law of Motion states that every object will continue in its state or uniform motion in a straight line unless a resultant force acts on it. Inertia Reluctance of the object to change its state of rest or motion, due to its mass . N2L Newton’s Second Law of Motion states that when a resultant force acts on an object of a constant mass, the object will accelerate in the direction of the resultant force. N3L Newton’s Third Law of Motion states that if body A exerts a force on body B, then body B will exert an equal and 𝐹 𝐴𝐵 opposite force on body A. 𝐹 𝐵𝐴 Friction Contact force that opposes or tends to oppose motion between surfaces in contact . Moment of a force, torque The moment of a force about a pivot is the product of the force F and the perpendicular distance d from the pivot to the line of action of the force . Principle of moments 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 .

Centre of gravity Imaginary point where the entire weight of the object seems to act . Stability of an object Measure of its ability to return to its original position. Pressure Force acting per unit area Pascal’s law If a pressure is applied to an enclosed l