Unit 3 – Energy! S8P2. Students will be familiar with the forms and transformations of energy. a. Explain energy transformation in terms of the Law of Conservation of Energy. b. Explain the relationship between potential and kinetic energy. c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics. d. Describe how heat can be transferred through matter by the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection)
How are ENERGY, WORK, and POWER related? Essential Question How are ENERGY, WORK, and POWER related?
What is Energy? P.442 Discover Activity: Hold a meter stick vertically with the zero end on the ground. Drop a tennis ball from the 50-cm mark and record the height to which it bounces. Drop the tennis ball from the 100-cm mark and record the height to which it bounces. Predict how high the ball will bounce if dropped from the 75-cm mark. How did you make this prediction? Test your prediction. Conclude – How does the height from which you drop the ball relate to the height to which the ball bounces?
What is Energy? P.442 Work is done when a force moves an object through a distance The ability to do work or cause change is called energy. Work is the transfer of energy; work and energy are measured in joules. If the transfer of energy is work, then power is the rate at which energy is transferred, or the amount of energy transferred in a unit of time.
Power = Energy transferred time Power is involved whenever energy is being transferred.
Kinetic Energy Moving objects do work, so they have energy. The energy an object has due to its motion is called kinetic energy. Kinetic energy of an object depends on its mass and its velocity – KE increases as mass increases. KE also increases as velocity increases. Recall the meanings of mass and velocity: Mass = A measure of how much matter is in an object. Velocity – Speed in a given direction.
Calculating Kinetic Energy Kinetic energy = ½ x Mass x Velocity2 Changing the velocity of an object will have a greater effect on its kinetic energy than changing its mass by the same factor because velocity is squared.
Potential Energy Stored energy that results from the position or shape of an object is called potential energy. This type of energy has the potential to do work. Let’s see an example of Kinetic and Potential Energy at work!
Gravitational Potential Energy is related to an object’s height, and is equal to the work done to lift it. The more an object weighs, or the greater the object’s height, the greater its GPE GPE = Weight x Height
Elastic Potential Energy Is the potential energy associated with objects that can be stretched, or compressed. Roadrunner Energy Video Link
Energy Skate Park
Bill Nye the Science Guy Yes, even Bill loves to demonstrate Kinetic and Potential energy!
Can You ANSWER the Essential Question? How are ENERGY, WORK, and POWER related?
Essential Question: Differentiate between kinetic and potential energy.
Gravitational Potential Energy Elastic Potential Energy Warm-Up: Venn Diagram Gravitational Potential Energy Elastic Potential Energy
Standard: S8P2c Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics.
Essential Question: How are the different forms of energy related?
Mechanical Energy The form of energy associated with the position and motion of an object Mechanical Energy = Potential energy + Kinetic Energy
Thermal Energy The total potential and kinetic energy of the particles (atoms and molecules) in an object. Also called HEAT Energy!!!
Electrical Energy The energy of electric charges – can be a form of kinetic or potential depending on whether the charges are moving or stored.
Chemical Energy Is potential energy stored in the chemical bonds that hold chemical compounds together (food, matches, cells).
Nuclear Energy Potential energy that is stored in the nucleus of an atom; released during a nuclear reaction (fission, fusion)
Electromagnetic Energy Energy that travels in waves, having some electrical and some magnetic properties. Also called Sound and Light/Radiant Energy!!!
Remember MR. CHEN M-MECHANICAL ENERGY R – RADIANT (ELECTROMAGNETIC/LIGHT&SOUND) C-CHEMICAL ENERGY H-HEAT ENERGY (THERMAL) E-ELECTRICAL ENERGY N-NUCLEAR ENERGY
Essential Question: How are different forms of energy related?
OPEN YOUR TEXTBOOK TO P.454!!!!!! Standard: S8P2a Explain energy transformation in terms of the Law of Conservation of Energy. OPEN YOUR TEXTBOOK TO P.454!!!!!!
Energy Transformation A change from one form of energy to another Multiple Transformations – A series of energy transformations is needed to do work. Ex: Mechanical energy used to strike a match is transformed to thermal energy, releasing stored chemical energy, which is transformed to thermal energy and electromagnetic energy. Single Transformations – One form of energy needs to be transformed into another to get work done. Ex: Toaster transforms electrical energy to thermal energy to toast your bread.
Transformations Between Potential and Kinetic Energy Demonstration
Law of Conservation of Energy When one form of energy is transformed to another, no energy is destroyed in the process. Energy cannot be created or destroyed. Friction transforms mechanical energy to thermal energy!
Roller Coaster Activity Instructions Watch this video first! Now read the instructions on the worksheet that your teacher gives you.
Einstein’s Theory of Relativity Einstein theorized that matter can be transformed to energy because destroying just a small amount of matter releases a huge amount of energy. He MAY be wrong according to recent research...!!! In some situations, energy alone is not conserved; however, since matter can be transformed to energy, scientists say matter and energy together are always conserved.