Physics Past Paper PDF

Newton's Laws of Motion: 1. First Law: Objects remain at rest unless acted upon by an external force. 2. Second Law: Force equals mass times acceleration (F=maF). 3. Third Law: Every action has an equal and opposite reaction. Forces: A force is a push or pull measured in Newton...

Newton's Laws of Motion: 1. First Law: Objects remain at rest unless acted upon by an external force. 2. Second Law: Force equals mass times acceleration (F=maF). 3. Third Law: Every action has an equal and opposite reaction. Forces: A force is a push or pull measured in Newton's (N). Effects of forces: Can change an object's speed, direction, shape, or cause rotation and motion. Types of Forces: Contact forces: Friction, tension, compression. Non-contact forces: Gravitational, electrostatic, and magnetic forces. Balanced vs Unbalanced Forces: Balanced: Forces are equal, causing no movement. Unbalanced: One force is greater, causing movement or change. Weight and Mass: Mass: amount of matter in a object Weight: Force due to gravity FORMULA: Mass (kg) x 9,8 (Earth gravitational acceleration ‘g’) = Weight (in Newtons ‘N’) Magnetic and Electrostatic Forces: Magnetic forces act between magnets. Electrostatic forces act between charged objects, causing attraction or repulsion. Resistors: limit the flow of electric current in circuits Resistance: Measured in Ohms (Ω), resistance is the opposition to the flow of electric charge. High resistance allows less current to flow, while low resistance allows more current. Factors Affecting Resistance: 1. Material: Different materials have different resistances. 2. Length: Longer conductors have higher resistance. 3. Thickness: Thicker conductors have lower resistance. 4. Temperature: Higher temperatures increase resistance. Types of Resistors: 1.Fixed Resistors: Provide constant resistance. 2.Variable Resistors: Include devices like rheostats (for adjusting resistance) and light-dependent resistors (LDRs), which change resistance based on light levels. 3.Diodes: allow current to flow in only one direction. Measurement Instruments: Ammeter: Measures current in series. Voltmeter: Measures voltage in parallel. Materials and Their Uses: 1.Nichrome and Tungsten: Used in resistors due to their specific resistance properties. 2.Semiconductors: used in electronic devices such as computer chips. 3.Insulators: Prevent current flow and are used for safety. Basic Elements of Electric Circuits: 1. Voltage Source: Provides the push for current to flow (e.g., battery). 2. Load: Uses electrical energy (e.g., lightbulbs, appliances). 3. Conductive Path: Connects the voltage source to the load (e.g., wires). Series Circuits: - Resistance: Increases with more resistors; results in reduced current and dimmer bulbs. Parallel Circuits: - Resistance: Decreases with more resistors; results in increased current and brighter bulbs. - Advantage: If one component fails, others continue to function. Power stations: convert fuel sources into electricity. Coal Power: Coal heats water to create steam, which drives a turbine and generates electricity. Nuclear Power: Similar to coal, but uses nuclear fission to produce steam. Hydropower: Water stored in dams is released to turn turbines and generate electricity. Alternative Energy Sources 1. Wind: Wind turbines convert wind into electrical energy, though they can be costly and disruptive. 2. Solar: Solar panels and heliostats harness the sun’s energy to generate electricity. 3. Wave: Wave energy converters use the ocean's motion to generate electricity, though the technology is still challenging to implement. Power Grid and Surges  National electricity grid: A network connecting power stations to supply electricity across South Africa. Power surges: occur when voltage exceeds normal levels Grid overload: happens when demand exceeds capacity, causing blackouts. Grid Network: A complex system where problems in one area can affect others. It’s crucial to manage power distribution to ensure stability. Topic 15: Cost of Electrical Power and Power Consumption Power: The rate at which work is done. Electrical Power: The rate at which electricity is supplied to an appliance. Measured in watts (W) or kilowatts (kW). Power rating: Tells how much electricity an appliance uses. Cost of electricity: Formula: Cost=power rating of appliance (KW) ×hours used× price of electricity If power rating is in watts then divide by 1000 to get kilowatts Environmental Impact of Electricity Consumption Higher electricity use requires burning more coal, leading to: 1. Increased air pollution. 2. Need for more power stations. Saving electricity is important to reduce pollution and costs. How to Save Electricity 1.Use low wattage, energy-saving light bulbs. 2.Install solar water heaters instead of electric geysers. 3.Dry clothes in the sun instead of using a tumble dryer. Solar water heaters: Installed on low-cost houses to reduce water heating costs.Passive houses: Designed to reduce energy consumption by using natural sunlight and insulation techniques. Earth's Spheres: 1. Atmosphere: The layer of gases surrounding Earth. 2. Hydrosphere: All water in various forms on Earth’s surface. 3. Lithosphere: The solid rock and soil 4. Biosphere: All living organisms and their interactions with the other spheres. Layers of the Earth: Crust: The outermost, thin layer made of solid rock and soil. Contains various minerals Mantle: The thickest layer, composed of two parts: an outer cooler layer and an inner layer of hot, liquid magma. Core: The innermost part, primarily made of iron, with two sections: Outer Core: Liquid and very hot. Inner Core: Solid and extremely hot. Crust Composition: Elements: Eight elements make up most of the Earth's crust. Minerals: Naturally occurring elements or compounds found in the crust, vital for various resources Soil Formation: Resulting from the weathering of rocks, soil contains minerals from the parent rock and is essential for plant photosynthesis. Composed of weathered rock, air, and water; main types include sand, clay, and loam. Types of Rocks: 1. Igneous: Formed from cooled magma. 2. Metamorphic: existing rocks change due to heat. 3. Sedimentary: Formed from layers of deposited particles. The Rock Cycle: Igneous Rock Formation: Magma cools and hardens; can occur in the crust or from volcanic eruptions. Sedimentary Rock Formation: Weathered rock particles are transported, deposited in layers, and compressed over time. Metamorphic Rock Formation: Heat from magma alters existing rocks, which can then be transformed back into magma. Examples: Igneous Rocks: Granite and kimberlite Sedimentary Rocks: Shale and limestone Metamorphic Rocks: Slate and marble Mineral Sources: Platinum, Chrome, and Diamonds: Found in igneous rock. Gold: Primarily found in sedimentary rock but originates in igneous rock  Mining Process: Definition: Mining is the extraction of ore from the Earth. Methods: ○ Blasting: Creating large holes or tunnels with drills and explosives to extract minerals. ○ Chemical Extraction: Using chemicals to extract minerals from rock. Refining Minerals: Physical Methods: ○ Gold Sluicing: Shoveling sand and gravel into a sluice box, where fine gold particles are captured. ○ Gold Panning: Swirling sand and gravel in a pan to separate gold. Chemical Methods: Dissolving ore with chemicals to extract minerals, followed by refining to remove impurities using heat and oxygen. Mining in South Africa: Home to a significant portion of the world’s mineral reserves: high in platinum, manganese, chrome and some vanadium and gold. Environmental Impact: Mining creates large amounts of waste rock, stored as mine dumps, which may contain hazardous chemicals like cyanide. Mining can damage farmland, wildlife, and cultural heritage sites. Water Pollution: Acid mine drainage occurs when mines fill with water, contaminating it with harmful substances. Active mines manage water to prevent contamination, but closed mines can lead to environmental hazards. Negative impact on mine workers: miners are away from home and family and it is a very dangerous job which could result in death Composition of the Atmosphere: The atmosphere is a mixture of gases held around Earth by gravity, essential for life. Layers of the Atmosphere: 1. Troposphere: ○ Lowest layer ○ Contains most of the atmosphere's mass and all weather phenomena. ○ Temperature decreases with altitude; most water vapor found here. 2. Stratosphere: ○ Second layer  ○ Contains the ozone layer(O3) which absorbs harmful UV radiation, protects life, and increases temperature in this layer. 3. Mesosphere: ○ Third layer ○ Very cold and thin air; burns up small rocks, causing shooting stars. 4. Thermosphere: ○ Fourth layer ○ Extremely thin air; absorbs UV rays and reflects radio waves. Satellites orbit here, temperature is very high. Temperature and Density: Temperature varies across layers, with some increasing and others decreasing with altitude. Density decreases as you move away from Earth. Greenhouse Effect: A natural greenhouse effect where UV rays are trapped by the ozone layer with greenhouse gases (GHGs) like carbon dioxide, methane, and water vapour, warming the planet. This is essential for life because without it we would freeze to death. Global Warming: An increase in GHGs leads to excessive heat retention, causing the "enhanced greenhouse effect," resulting in global warming. This leads to climate change, rising sea levels, food shortages, and biodiversity loss. Key Point: The main cause of rising CO2 levels is often linked to human activities, such as fossil fuel combustion and deforestation. The Milky Way Galaxy: The Milky Way is a massive collection of stars, dust, and gas, held together by gravity. Greeks named it because it looks like spilled milk Birth of a Star: Stars are born in nebulae, which are vast clouds of gas and dust, primarily composed of hydrogen and helium. Gravity causes part of the nebula to collapse into a protostar. This leads to the onset of nuclear fusion. Stellar evolution: is a process where stars undergo a sequence of changes during lifetime. Stars only exist for finite period. Nuclear Fusion: hydrogen is transformed into helium, generating immense pressure and heat, and releasing energy into space. This process sustains a star's life. Life of a Star: Stars shine due to nuclear fusion in their cores. As they form, they reach a state where the energy produced equals the energy radiated, entering the main sequence phase The characteristics and lifespan of a star depend on its mass. Death of a Star: 1. Red Giant: As stars exhaust their hydrogen fuel, they collapse and heat up, igniting surrounding hydrogen, causing outer layers to expand into a red giant. 2. Planetary Nebula: As the star sheds its outer layers due to solar winds, it forms a planetary nebula 3. White Dwarf: After shedding its outer gases, the remaining core cools into a white dwarf, primarily composed of carbon and oxygen, with a thin layer of helium. Explain the life of a star: Stars are born in a planetary nebulae. Gravity causes part of the nebula to collapse into a protostar. This leads to the onset of nuclear fusion where hydrogen is transformed into helium and releasing energy into space, this sustains a star's life. As they form, they reach a state where the energy produced equals the energy radiated, entering the main sequence phase. As stars exhaust their hydrogen fuel, they collapse and heat up, causing outer layers to expand into a red giant. As the star sheds its outer layers due to solar winds, it forms a planetary nebula and once shedding its outer gases, the remaining core cools into a white dwarf, primarily composed of carbon and oxygen, with a thin layer of helium.