Grade 10 Unit 3 - Winter Chills Notes PDF

Grade 10 unit 3 - Notes Unit 3 Winter Chills Grade 10 unit 3 - Notes Unit Introduction In this unit you will explore energy and how it can be conserved effectively. Understanding Student will be able to understand and or calculate the following - L...

Grade 10 unit 3 - Notes Unit 3 Winter Chills Grade 10 unit 3 - Notes Unit Introduction In this unit you will explore energy and how it can be conserved effectively. Understanding Student will be able to understand and or calculate the following - Law Of Conservation Of Energy in different contexts and be able to calculate the conservation of energy effectively - Understand the difference between useful and consumed energy - Have the ability to calculate energy efficiency - Understand the difference between heat and temperature. Content Textbook - page 70 to 74 3.1 Prior Knowledge 3.2 Types of energy 3.3 Law of conservation of energy 3.4 Energy efficiency 3.5 Distinction between temperature and heat Grade 10 unit 3 - Notes 3.1 Prior Knowledge What is energy? Energy is the amount of work an object can do or store What is work? Work is the amount of force applied to an object over a distance What are the units for energy? JOULES (J) Grade 10 unit 3 - Notes Energy Energy falls into two main categories potential and kinetic energy. Potential Is the amount of energy an object has at rest Kinetic Is the energy an object has as it moves Energy Transformation and Transfer Transformations of energy When energy changes of one form of energy to another Example A light bulb The initial energy of a light bulb in electrical energy when the light bulb is turned on the electrical energy is transformed into radiant and thermal energy. Transfer of energy When the same energy is moved from one object to another Example Kinetic energy when the player in black tackles the player in green the kinetic energy from the player in black is transferred to the player in green. Grade 10 unit 3 - Notes Energy through a system In the diagram below we see the forces that are in action while the newton’s cradle is in use. 1. At the start of the system the red ball has potential energy before it is released 2. When the ball is released the potential energy transforms into kinetic energy. 3. When the first ball makes contact with the second ball the kinetic energy transfers to the next ball and then the next until the end of the balls Grade 10 unit 3 - Notes 4. The last ball will then start transforming the kinetic energy into potential energy as it swings up. 5. Once all the kinetic energy is transformed into potential the system is ready to start again. In a perfect system (which doesn’t exist) the ball would swing forever. As no energy In reality some energy is dissipated (released) into different types of energy, Sound energy from the balls hint one another and thermal energy from friction. It also explains the first law of thermodynamics (the law of conservation of energy) Energy is never created or lost it is either transformed or transferred Grade 10 unit 3 - Notes 3.3 Law Of Conservation Of Energy The amount of energy at the start of a system is the same as the amount energy at the end of a system. The perfect system What happen in a real system Grade 10 unit 3 - Notes Qualitatively Explain the Law Of Conservation Of Energy Example 1. When a light bulb is turned on it uses 1500 J of electrical energy. The electrical energy is consumed equal to 1000 J of useful radiant energy and 500J of dissipated thermal energy. 𝐸𝑛𝑒𝑟𝑔𝑦 𝑖𝑛 = 𝐸𝑛𝑒𝑟𝑔𝑦 𝑜𝑢𝑡 𝐸𝑙𝑒𝑐𝑡𝑟𝑖𝑐𝑎𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 = 𝑅𝑎𝑑𝑖𝑎𝑛𝑡 𝐸𝑛𝑒𝑟𝑔𝑦 + 𝑇ℎ𝑒𝑟𝑚𝑎𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 1500 𝐽 = 1000𝐽 + 500𝐽 Grade 10 unit 3 - Notes 3.4 Energy Efficiency Energy efficiency is a measure of how effectively energy input is converted into useful output without being wasted. It is typically expressed as a percentage, where a higher percentage indicates more efficient energy use. For example, if a light bulb converts 90% of the electrical energy it receives into light and only 10% is lost as heat, it is 90% energy efficient. In general, the formula for energy efficiency is: 𝑈𝑠𝑒𝑓𝑢𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝐸𝑛𝑒𝑟𝑔𝑦 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 = 𝐶𝑜𝑛𝑠𝑢𝑚𝑒𝑑 𝑒𝑛𝑒𝑟𝑔𝑦 × 100 Maximizing energy efficiency helps conserve resources, reduce costs, and minimize environmental impact by reducing unnecessary energy consumption. Useful energy - is the energy used for doing something e.g. Radiant energy is the point of a light bulb Consumed Energy - is the total amount of energy used Dissipation = Useless energy Grade 10 unit 3 - Notes Example A lawnmower engine converts chemical energy from gasoline into mechanical energy to power the blades. It consumes 700 kJ of chemical energy, but 280,000 J are lost as heat and sound. What is the energy efficiency of the lawnmower engine? Consumed Energy = 700 kJ 1. Find the total energy consumed and the useful energy Useful Energy = 700-280 = 420 kJ 2. Make sure that the units are the same 3. Add them to the equation and solve 𝑈𝑠𝑒𝑓𝑢𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝐸𝑛𝑒𝑟𝑔𝑦 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 = 𝐶𝑜𝑛𝑠𝑢𝑚𝑒𝑑 𝑒𝑛𝑒𝑟𝑔𝑦 × 100 420 𝐸𝑛𝑒𝑟𝑔𝑦 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 = 700 × 100 𝐸𝑛𝑒𝑟𝑔𝑦 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 = 60% Grade 10 unit 3 - Notes Improving the energy efficiency of electrical appliances can be achieved through several strategies that reduce wasted energy and increase the useful energy output. Here are some common approaches: 1. Use Energy-Efficient Technology Look for appliances with energy-efficient technology, such as LED lighting or inverter motors, which use less energy. Many energy-efficient models are labeled with an Energy Star rating or similar efficiency certifications. 2. Implement Smart Control Systems Appliances with smart controls can adjust their energy consumption based on usage patterns. For example, smart thermostats or smart plugs can turn appliances off when they are not in use, reducing standby energy consumption. 3. Upgrade Insulation and Materials For appliances like refrigerators, ovens, or water heaters, better insulation reduces heat loss. This allows the appliance to maintain temperatures with less energy. 4. Regular Maintenance Keeping appliances clean and well-maintained ensures they run more efficiently. For instance, a refrigerator with clean coils consumes less energy, and a dryer with a lint-free filter dries clothes faster with less electricity. Grade 10 unit 3 - Notes 5. Optimize Usage Settings Many appliances offer energy-saving modes or adjustable settings. For instance, using lower heat settings on washing machines, dishwashers, and dryers, or setting refrigerators and freezers to optimal temperatures, can reduce energy consumption. 6. Reduce Standby Power Consumption Appliances often draw power even when they’re turned off, known as "phantom load." Using a power strip with an on/off switch or unplugging devices when they’re not in use can help reduce this wasted energy. 7. Consider Renewable Energy Sources In homes or buildings with renewable energy systems like solar panels, running appliances during peak sunlight hours can maximize energy efficiency and lower reliance on grid electricity. These methods collectively help lower energy use, save costs, and decrease the environmental impact associated with energy production. Grade 10 unit 3 - Notes 3.5 Distinction between Temperature and Heat Thermal Energy Thermal energy is the amount of movement particles have inside something (an object or a system) Temperature A measure of the amount of thermal energy Heat Heat is the movement of Thermal energy from an area of high energy to low energy Examples Why is ice cold? Ice feels cold to the touch because thermal energy is transferred from a hand (high thermal energy) into the ice (low energy). This is an example of heat. In the example the ice feeling cold is what you would expect to happen as you know that ice has a lower temperature than you. Grade 10 unit 3 - Notes You have two cubes which are the same size in front of you one is made of plastic the other is made of metal. They have been resting next to each other for 24 hours. 1. Will the cubes feel like they have a different temperature? 2. What can you predict about their temperature? 3. Explain you answers Answers 1 - The iron will feel colder than the plastic 2 - I would predict that they have the same temperature 3 - Although the iron would feel colder than the plastic they will both be the same temperature as the room. The reason for this is because the iron will have a lower thermal energy than the plastic so when touched there is a greater amount of heat transfer from your body into the iron than the plastic. Grade 10 unit 3 - Notes The importance of thermal energy on particles is shown below The increase of thermal energy As a substance is heated it is collecting energy. At a certain point the energy overcomes the forces of attraction between the particles. This happens at the boiling point and the melting point of a substance. Point of interest A substance does not have to be at its boiling point for evaporation to take place. This is why clothes dry on a washing line. Boiling only happens when the rate of evaporation is very high The releases of thermal energy Energy must be transferred from a substance to the environment for condensing and freezing to happen. During these changes of state the particles lose energy as forces of attraction form between them. Grade 10 unit 3 - Notes