0. H2.Physics.Definition List.2023 20230301

CJC Definition List 2023 1 | P a g e CATHOLIC JUNIOR COLLEGE 9749 H2 PHYSICS DEFINITION LIST Measurements Forces Dynamics Kinematics Work, Energy and Power Motion in a Circle Gravitational Field Oscillations Waves Superposition Thermal Physics Electric Field Current of Electricity / D.C. Circuits Alternating Current Electromagnetism and Electromagnetic Induction Quantum Physics Nuclear Physics

CJC Definition List 2023 2 | P a g e Measurements Random Error: is an error which gives a scatter of readings about an average value. It has an equal chance of being positive or negative and can be reduced by averaging. Systematic Error: is a constant deviation of readings in one direction. All measurements will be too high or too low by a certain amount . It can be reduced by correct laboratory practice. Precision (of a set of readings): Precision (of an instrument) is the degree of closeness of the readings with one another. It is associated with small random error. a term used to describe the level of uncertainty in an instrument’s scale. High precision instruments have small scale divisions. Accuracy (of a set of readings): Accuracy (of an instrument): is the degree of closeness of the average value of the readings to the true value. It is associated with small systematic error. is the closeness of a reading on an instrument to the true value of the quantity being measured. An accurate instrument will give readings close to the true values. N22/II/Q2ai[1] Vector Quantity: is a quantity having both magnitude and direction. Scalar Quantity: is a quantity that has magnitude only, not direction. Kinematics Distance: is the total length of the actual path travelled by an object in motion. It is a scalar quantity. Displacement: is the straight l ine distance of an object or a point, in a specified direction, from some reference point. The specified direction is directed from the reference point to that object’s position or that point. Displacement is a vector quantity. Speed: is the rate of change of distance with respect to time. Velocity: is the rate of change of displacement with respect to time. N15/III/6ai [1] Acceleration: is the rate of change of velocity with respect to time.

CJC Definition List 2023 3 | P a g e Dynamics Newton's First Law of Motion: A body stays at rest or continues to move at constant velocity unless a resultant force acts on it. N10/II/1a [1] Newton's Second Law of Motion: the rate of change of momentum of a body is directly proportional to the net force acting on it, and , the direction of momentum change is in the direction of the net force. Newton's Third Law of Motion: Whenever a force acts on a body, an equal but oppositely directed force of the same kind acts on another body. Characteristic of Action-Reaction Pair: The action-reaction pair forces • are of the same nature • are of equal magnitude • act along the same line but opposite directions • act on different bodies N12/III/6ai [1] Linear Momentum: is the product of the mass of an object and its velocity. N10/III/6a [2] Force: is the rate of change of momentum of an object which is free to move, and acts in the direction of the change in momentum. The newton is the SI unit of force. One newton is that forc e required to give a mass of 1 kilogram an acceleration of 1 metre per second squared in the direction of the force. Moment of a Force: Moment of a force about any point is the turning effect of a force which is equal to the product of the force and the perpendicular distance from that point to the line of action of the force. Couple: consists of two forces of equal magnitude but acting in opposite directions whose lines of action are parallel but separate. Torque of a Couple: is the turning effect of the couple. For two equal but opposite parallel forces, each of magnitude F, with their lines of action separated by a perpendicular distance d, the magnitude of the turning effect of the couple is the product of F and d. N18/II/1a[1] Principle of Moments: states that for a body to be in equilibrium, the sum of clockwise moments about any pivot must be equal to the sum of anticlockwise moments abo ut that same pivot. N19/II/1a [2] Equilibrium: An object which, under the action of a number of forces, remains at rest or moving with a constant velocity and if in rotation is rotating at constant angular velocity is said to be in equilibrium.

CJC Definition List 2023 4 | P a g e N15/III/Q1a [2] Two conditions for equilibrium: 1. The algebraic vector sum of the forces acting on the object in any direction must be zero. 2. The algebraic vector sum of the moments of the forces in the object about any point must be zero. Mass: is a measure of a body's resistance to change in velocity. Density: is the mass per unit volume of a substance Weight: is the force acting on a mass due to a gravitational field. Apparent Weight: is the normal contact force experienced by an object in contact with a surface. Weightlessness: the absence of normal contact force acting on an object. N13/II/2a [1] Impulse: is the product of the average force acting on an object and the duration of time for which the force acts. N12/III/6bi [2] Principle of Conservation of Linear Momentum: The total linear momentum of a system will remain constant if no net external force acts on it. Isolated system: a system which has no external force and no external torque acting on it, and, has no transfer of mass in and out of it. Head-on collision: the velocities of the colliding bodies are collinear both before and after impact. Elastic collision: a collision in which the total kinetic energy of the colliding bodies is conserved before and after the collision. Consequence of system in elastic collision is that the Relative velocity of separation is equal to the relative velocity of approach. Inelastic collision: a collision in which the total kinetic energy of the colliding bodies is not conserved before and after the collision. Perfectly inelastic collision: a collision in which the total kinetic energy of the colliding bodies is not conserved before and after the collision, and, the colliding bodies stick together after the collision. Forces Friction: is a contact force that opposes the relative motion between two bodies in contact, or, tends to oppose one body from moving relative to the other.

CJC Definition List 2023 5 | P a g e N18/II/2a[1] Hooke’s Law: states that force is proportional to its extension, provided the limit of proportionality has not been exceeded. Spring Constant (also known as ‘elastic constant’): is t he constant of proportionality between force and extension for a sample of material that has not been stretched to such an extent that it has exceeded the elastic limit. Upthrust: is the net upward force exerted by a fluid on a body as a result of the body being immersed (either partially or totally) in the fluid. Archimedes’ Principle: states that when an object is totally or partially immersed in a fluid, it experiences an upward force (upthrust) equal to the weight of fluid displaced. Principle of Flotation: an object floats in a fluid when it displaces a weight of fluid equal to its own weight. Centre of Gravity (CG): is the point at which the whole weight of a body may be thought to act. Work, Energy and Power N10/III/6bii Work: is the product of the average force acting on an object and the displacement moved in the direction of the force. Energy: is the stored ability to do work. The joule: is the SI unit of energy or work done. One joule of work is done when a force of one newton moves its point of application by one metre in the direction of