Grade 8 Physics

Physics 8 Lesson 29: Questions and exercises to summarize Chapter II Thermodynamics 1. Theoretical summary 1.1. Review questions a. How are substances formed? Substances are made up of separate particles called atoms and molecules. b. State two characteristics of the atoms and molecules that make up the substances studied in this … [Read more...] about Physics 8 Lesson 29: Questions and exercises to summarize Chapter II Thermodynamics

Physics 8 Lesson 28: Heat engine 1.2. Four stroke engine 1.3. Engine performance The efficiency of a heat engine is determined by the ratio between the heat successfully converted to mechanical energy and the heat released by the burned fuel. - In there: A: The work done by the engine (J), is equal to the amount of heat converted into mechanical energy. Q: … [Read more...] about Physics 8 Lesson 28: Heat engine

Physics 8 Lesson 27: Conservation of energy in mechanical and thermal phenomena 1. Theoretical summary 1.1. Transfer of mechanical and thermal energy from one object to another: Describe the transfer of mechanical and thermal energy in the following phenomena:- The steel ball rolling from the inclined chute collides with the wood, causing the wood to move.Drop a piece of … [Read more...] about Physics 8 Lesson 27: Conservation of energy in mechanical and thermal phenomena

Physics 8 Lesson 26: Heat capacity of fuel 1. Theoretical summary 1.1. Fuel Some common fuels: Coal, firewood, oil, gas are fuels Eg: Coal, firewood, oil, gasoline, alcohol, gas... 1.2. Heat capacity of fuel VD: The calorific value of kerosene is \(44.10^6(J/kg)\) 1.3. The formula for calculating the amount of heat released by the burned … [Read more...] about Physics 8 Lesson 26: Heat capacity of fuel

Physics 8 Lesson 25: Heat balance equation 1. Theoretical summary 1.1. Principle of heat transfer Heat transfers from an object with a higher temperature to an object with a lower temperature. Heat transfer occurs until the temperatures of the two objects are equal. The heat released by one object is equal to the heat absorbed by the … [Read more...] about Physics 8 Lesson 25: Heat balance equation

Physics 8 Lesson 24: Calculation formula 1. Theoretical summary 1.1. On what factors does the heat absorbed by an object to heat up depend? - Prediction: Depends on 3 factors: Mass of the object The temperature rise of the object Substances that make up objects. a) The relationship between the amount of heat absorbed for the object … [Read more...] about Physics 8 Lesson 24: Calculation formula

Physics 8 Lesson 23: Convection- Heat radiation 1. Theoretical summary 1.1. Convection a) Experiment: b) Answer the question: - C1: Does the purple water move in a stream from the bottom up and then from the top or does it move chaotically in all directions? The purple water moves in a stream from the bottom up and then from the top. - C2: Why … [Read more...] about Physics 8 Lesson 23: Convection- Heat radiation

Physics 8 Lesson 22: Heat conduction 1. Theoretical summary 1.1. Heat conductivity Conduction is the transfer of heat energy from one part of an object to another 1.2. Thermal conductivity of substances a) Experiment 1: - Experimental comments + C4: Do the nails fall at the same time? + C5: What does that phenomenon show? Of these … [Read more...] about Physics 8 Lesson 22: Heat conduction

Physics 8 Lesson 21: Heat energy 1. Theoretical summary 1.1. Heat energy Thermal energy: The sum of the molecular kinetic energy of all the molecules that make up an object is called heat energy All objects have heat energy because the molecules that make up the object are always in motion. Thermal energy depends on temperature: The … [Read more...] about Physics 8 Lesson 21: Heat energy

Physics 8 Lesson 20: Are atoms and molecules moving or at rest? 1. Theoretical summary 1.1. Brown's Experiment a) Experiment: 1827 - The botanist (British) Berao observed pollen grains in water with a microscope and discovered that they were in constant motion in all directions. When pounded or boiled, the pollen grains are still in constant … [Read more...] about Physics 8 Lesson 20: Are atoms and molecules moving or at rest?