SCIENCE-QUARTER-1-REVIEWER.pdf

SCIENCE QUARTER 1 REVIEWER Types of FORCES Friction - the force generated by two surfaces that contact and slide against each other. Tension - the force transmitted through a rope, str...

SCIENCE QUARTER 1 REVIEWER Types of FORCES Friction - the force generated by two surfaces that contact and slide against each other. Tension - the force transmitted through a rope, string or wire when pulled by forces acting from opposite sides. Gravity - the force that attracts any two objects with mass. Normal - the force that surfaces exert to prevent solid objects from passing through each other. Applied – the force that is applied to an object by a person or another object. Newton’s LAWS OF MOTION Law of Inertia - “An object at rest will remain at rest and an object in motion will remain in motion unless acted upon an external force.” - It is an object’s resistance to any change in motion (LAZINESS) - Mass is a measure of inertia. More the mass, more will be the inertia. Law of Acceleration - The acceleration of an object depends on two things: force and mass. - The acceleration of an object is directly related to the net force and inversely related to its mass. - Basic Formula: o F = ma o m = F/a o a = F/m Law of Interaction - “For every action, there is an equal and opposite reaction.” - Whenever an object exerts a force upon another object, the other object exerts an equal and opposite force to the first object. BALANCED and UNBALANCED Force Balanced Force Unbalanced Force Equal in magnitude Not equal in magnitude Net force equates to zero Net force is non-zero No change in motion Have change in motion Equal forces act on the Unequal forces act on the body in the opposite body in the opposite direction direction Combining Forces: Formula: Fnet = Fg + Fn Like signs: + +/ - - (Add) Unlike signs: + -/ - + (Subtract) KINETIC & POTENTIAL Energy Energy - the ability to do any work. - It can’t be created or destroyed but it can be altered. 2 Forms of Energy Kinetic Energy - Energy of motion - A moving object’s kinetic energy depends on its mass and velocity. - Formula: ½ mv2 Potential Energy - Stored energy - Type of energy that possess due to their position or height relative to a reference point. - Formula: o PE = (Mass) (Gravity: 9.8 m/s2) (Height) or mgh o h = PE/mg o m = PE/gh SOUND Waves It is the energy things produce when they vibrate (move back & forth quickly) An example of a longitudinal wave  o Longitudinal wave – a wave that is usually created by pulling and pushing a medium. Sound NEED a medium to propagate. Factors that affect the speed of sound: - State of matter - Temperature - Rigidity of the medium Formula of the speed of sound: o v = 331 m/s + 0.6 m/s/C (T) Echo – reflected sound. Reflection – described as the turning back of a wave as it hits the barrier. Refraction – described as the change in speed of sound when it encounters a medium of different density. Amplitude – relative strength of sound waves (transmitted vibrations), which we perceive as loudness or volume. Reverberation – refers to multiple reflections or echoes in a certain place. Vibration – repeated back-and-forth motion of a particle when displaced from one equilibrium position. LIGHT Waves The visible spectrum is the band of the electromagnetic spectrum that is visible to the human eye. Lights can travel in a vacuum o Vacuum - a volume empty of matter, sometime called “free-space” Wavelength is inversely proportional to the frequency and energy of light. While frequency and energy are directly proportional to each other. Red has the longest wavelength and has the lowest frequency and energy. It is also the least bend color. Violet has the shortest wavelength and has the highest frequency and energy. It is also the most bend color. Properties of Light: Reflection - the bouncing back of light when it strikes a smooth surface. Refraction - the bending of light rays when it travels from one medium to another. Dispersion - the splitting of white light into its constituent colors due to the refractive index of the surface and the wavelength of the light. THERMAL Energy The form of energy transferred from one object to another due to the temperature difference between them. It refers to the total kinetic energy of the particles in a substance due to their motion. Phases that absorb heat: - Melting, Evaporation, Sublimation Phases that release heat: - Freezing, Condensation, Deposition Temperature vs. Heat Temperature Heat Unit: Celsius, Fahrenheit, Unit: Calorie, Joules Kelvin Degree of hotness Quantity of hotness Symbol: T Symbol: Q Thermometer Calorimeter Average kinetic energy Total kinetic energy CURRENT vs. VOLTAGE Current - The flow of the electrical charge carriers in a wire or circuit. - The stream of charged particles. - The rate of flow of charged particles - Andre-Marie Ampere (1775-1836) - French physicist and mathematician. ✓ Founder of the science of classical electromagnetism Voltage - Electrical Potential Difference  - The difference of potential between two points in a circuit or battery - Also called “Electromotive force” - It causes the current to flow. o Alessandro Volta (1745-1827) ✓ Italian physicist, chemist, and pioneer of electricity and power. ✓ Invented the first electric battery in 1800. Current Voltage Symbol: I Symbol: V or E Unit: Ampere (A) Unit: Volt (V) 1 ampere = 1 1 volt = 1 Joule/Coulomb Coulomb/second Device: Ammeter Device: Voltmeter Resistance - A force that counteracts the flow of current. - It serves as an indicator of how difficult it is for current to flow. - Resistance values are expressed in ohms. - Current is directly proportional to the voltage and inversely proportional to the resistance. As the voltage increases the current increases, when the resistance increases (no. bulbs, wire) the flow of current decreases. - Formula: o V = IR o I = V/R o R = V/I Electricity - A type of energy that consists of the movement of electrons between two points when there is a potential difference between them. - It is known as electric current. o Michael Faraday (1791-1887) ✓ English scientist who studied the electromagnetism and electrochemistry. ✓ Known as the “Father of electricity.” SERIES and PARALLEL CIRCUIT Parallel Circuit - an electrical path that branches so that the current divides and only part of it flows through any branch. - If one of them fails or is disconnected, the rest of the circuit still works. Series Circuit - the circuit elements are arranged in a single path. This means that, if there are three resistors in series, the same current must flow through all 3. - If there is any fault or break at one of the bulbs, the bulbs connected in a series circuit will also be affected. Short circuit – It refers to a circuit condition in which a current takes path of less resistance or zero resistance. Grounded circuit – It refers to circuit condition where current travels from the positive conducting wire. Thermal hazard – It occurs when there is electrical overheating. Shock hazard – It occurs when electric current passes through a person. Octopus wiring – It is the jam packing of wires on an outlet. Fuse – It is made up of metal ribbon that will heat up and melt if the current exceeds its current rating. Double Insulation – It is made from an extremely poor conductor to create a safe path for the current to flow through. Circuit Breaker – Uses electromagnets and bimetallic strips to open a switch in cases of overloading. Earthing/Grounding – It is a system of connecting the metal casing of the appliance to earth and protects the user from a grounded circuit. Uninterruptable Power Supply (UPS) – An electrical safety device which provides emergency power to the load when there is unexpected power disruption.