Physics_6091_Power_Bank_version_2.0

‘O’ Level Physics Power Bank! Version 2.0

Definitions in Physics 6091 O‐Level Syllabus Topics Definition Measurements A physical quantity is one that can be measured and consists of a numerical magnitude and a unit. Each complete to-and-fro motion of an object is one oscillation. The Period T of a pendulum is the time taken for a complete oscillation. Kinematics Scalar quantities are physical quantities that have magnitude only. Vector quantities are physical quantities that possess both magnitude and direction. Speed is the distance moved per unit time. Displacement is distance travelled in a specified direction. Average speed is total distance travelled over total time. Velocity is the rate of change of displacement. Acceleration is the rate of change of velocity. Uniform Acceleration is the constant rate of change of velocity. Free fall is when an object falls and experiences only the gravitational force. Dynamics A force is a push or a pull that one object exerts on another. Newton’s 1st Law of motion states that every object will continue in its state of rest or uniform motion in a straight line unless a resultant force acts on it. {note : This is also known as Law of Inertia} Newton’s 2nd Law of motion states that 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. One Newton (1 N) is defined as the force that will produce an acceleration of 1 m s-2 on a mass of 1 kg. Newton’s 3rd Law of Motion states that for every action, there is an equal and opposite reaction. Friction is a force that opposes sliding motion between two surfaces in contact. Mass, Weight, Density Mass is a measure of the amount of matter or substance in an object. Density is the mass per unit volume of a substance. Weight is the gravitational force acting on a mass. Gravitational field is a region in which a mass experiences a force due to gravitational attraction. Gravitational field strength is defined as the gravitational force acting per unit mass on an object. {eg. g =10N/kg}

Topics Definition Inertia of an object refers to the reluctance of the object to change its state of rest or motion due to its mass. Turning effect of Force Moment of a force is the product of force and the perpendicular distance from the pivot to the line of action of the force. Principle of moments states that 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 centre of gravity of an object is defined as the point through which its whole weight appears to act. Stabil