Physics & Chemistry Notes Physics -Turning Effects Of Forces Definitions: 1. The moment of a force is the product of the force by the perpendicular distance from the pivot to the line of action of the force.2. The principal 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. Formulas:1. Moment of force = F x D2. Sum of clockwise moments about a pivot = Sum of anticlockwise moment about the same pivot (F2 x D2 = F1 x D1) Factors: 1. Turning effect or moment of a force is affected by the perpendicular distance of the force from the pivot, and the magnitude of the force. Units: 1. Moments = Newton-metre (Nm)

- Centre Of Gravity & Stability Definitions:1. Weight is the gravitational force acting on the mass of an object. 2. The centre of gravity of an object is a single point at which the weight of the object can be taken as acting through.3. Stability refers to the ability of an object to return to its original position after it has been tilted slightly. Formulas:1. Weight = Mass x Gravitational Field Strength (Mg) Factors: 1. Factors affecting stability include larger base area, and lower centre of gravity. Units: 1. Weight = Newton (N) Answering Formats:1. Stable equilibrium: The line of action of weight is acting within the base area of the object. This creates an anti-clockwise moment about the pivot, thus the object returns to its original position.2. Unstable equilibrium: The line of action of weight is acting outside the base area of the object. This creates a clockwise moment about the pivot, thus the object topples over. 3. Neutral equilibrium: The centre of gravity of the object remains at the same height wherever it is displaced, thus it is in neutral equilibrium.

- Waves Definitions:1. A wave is a disturbance that transfers energy from one place to another.2. Longitudinal waves are waves that travel parallel to the direction of the vibration of the particle. 3. Transverse waves are waves that travel perpendicular to the direction of the vibration of the particle. 4. Crests are the highest points of a transverse wave.5. Troughs are the lowest points of a transverse wave. 6. The amplitude A of a wave is the maximum displacement of a point from its rest position. (Loudness) 7. The wavelength of a wave is the shortest distance between any two points in a phase. 8. The period T of a wave is the time taken to produce one oscillation. 9. The frequency f of a wave is the number of complete oscillations produced per second. 10. Wave of speed v is the distance travelled by a wave per second. Formulas: 1. F = 1 / T2. V = f Units:1. Frequency = Hertz (Hz)2. Wavelength = 3. Wave Speed = m/s Answering Formats: 1. Difference between transverse and longitudinal waves: Transverse waves travel perpendicular to the direction of the vibration of the particle while longitudinal waves travel parallel to the direction of the vibration of the particle. 2. Similarity between transverse and longitudinal waves: Both waves transfer energy from one place to another without transferring the medium. Both waves are made up of periodic motion repeated at regular intervals.

- Sound Definitions:1. Sound is a form of energy that is transferred from one point to another as a longitudinal wave. 2. Compressions are regions where the medium's density is higher than the surrounding density. 3. Rarefactions are regions where the medium's density is lower than the surrounding density. 4. An echo is the repetition of a sound due to the reflection of the sound. Formulas:1. Speed of sound = 2 x distance / time taken Answering Formats:1. How compressions are rarefactions are set up: Layers of air are in undisturbed positions. When the prongs push outwards, a region of compression is produced. When the prongs move inwards, a region of rarefaction is produced. The prongs continue to vibrate (inward and outward) and a series of compressions and rarefactions is set up.2. How sound travel through air: When the source vibrates, energy is transferred to the layers of air in front of it and the layers of air will vibrate parallel to the direction of wave motion. Then the next layer of air will also vibrate and the process will repeat, forming an alternating series of compression and rarefactions. Sound is propagated as a longitudinal wave.

- Light Definitions:1. Incidence is the point at which the light ray hits the mirror or a surface. 2. Angle of incidence is equal to the angle of reflection.3. The incident ray, reflected ray, and normal to the reflecting surface all lie on the same plane. Formulas:1. Angle of incidence = Angle of reflection / Angle between the incident ray and the normal2. Angle of reflection = Angle of incidence / Angle between the reflected ray and the normal Answering Format:1. Two laws of reflection: Angle of incidence is equal to the angle of reflection. The incident ray, reflected ray, and normal to the reflecting surface all lie on the same plane.2. Properties of mirror images: The image is the same size as the object. The image is virtual. The image is upright. The distance of the image from the mirror is same to the distance of the object from the mirror. The image undergoes lateral inversion. Chemistry -Acids And Alkalis Definitions: 1. An acid is a substance that dissociates in water to produce hydrogen ions as the only positive ion.2. Bases are formed between metal and oxygen or metal and hydroxide. 3. An alkali is a base that is soluble in water. Formulas:1. Metals + Acids = Salt + Hydrogen*Unreactive metals include: Copper, Silver, Gold, Platinum2. Carbonates + Acids = Salt + Water + Carbon Dioxide*Observations: Bubbles can be seen, carbonate / metal dissolves and becomes smaller.3. Bases / Alkalis + Acids = Salt + Water (Neutralisation)4. Ammonium salt + Alkalis = Ammonia + Water + Salt*If the acid is hydrochloric acid, the salt name will end with chloride.*If the acid is nitric acid, the salt name will end with nitrate.*If the acid is sulfuric acid, the salt name will end with sulfate. 5. Hydrochloric Acid = HCL6. Sulfuric Acid = H2SO47. Nitric Acid = HNO38. Phosphoric Acid = H3PO49. Ethanoic Acid = CH3COOH Answering Format: 1. Test for Hydrogen gas: Insert a lighted splint into the gas. If the lighted splint is extinguished with a 'pop' sound, the gas is hydrogen gas.2. Test for Carbon Dioxide gas: Bubble the gas through limewater. If white precipitate is formed in limewater, the gas is carbon dioxide gas.3. Test for Ammonia gas: Place a piece of damp red litmus paper into the gas. If the damp red litmus paper turns blue, the gas is ammonia gas. Properties Of Acids: - Sour taste- Corrosive- pH value of less than 7- Conduct electricity when dissolved in water -Turns damp blue litmus paper red Properties of Alkalis:- Taste bitter and slippery- Corrosive- pH value of more than 7- Conduct electricity when dissolved in water- Turns damp red litmus paper blue

-The pH ScaleDefinitions:1. pH scales measures how acidic or alkaline a solution is.2. Indicators are chemical substances that change color when they are added to alkalis or acids.3. Universal Indicators is a mixture of several indicators which changes color at different pH value.pH Color Chart:Red = 0 to 2Orange = 3 to 4Yellow = 5 to 6Green = 7 to 9Blue = 10 to 11Purple-Violet = 12-14 -Atomic StructureDefinitions:1. Protons , neutrons and electrons are known as sub-atomic particles.2. Isotopes are atoms of the same element with the same number of protons and electrons, but different numbers of neutrons. Formulas:1. Number of neutrons = Number of nucleons (mass number) - Proton number2. Number of shells = Period3. Valence Number = Group NumberAnswering Format:1. Electrically neutral: An atom is electrically neutral as it has the same number of protons and electrons.2. Chemical Properties and Physical Properties of Isotopes: Isotopes have identical chemical properties but their physical properties are different. They have the identical chemical properties as they have the same number of electrons which are involved in chemical reactions. They have different physical properties as they have different mass.3. Unreactive and active gases: Noble gases (Helium, Argon, etc) are unreactive as they have already achieved a stable electronic configuration with full electron shells. Other atoms are reactive as they want to achieve a stable electronic configuration with full electron shells, by gaining, losing, or sharing valence electrons, which forms ions.