Transcript Slide 1
PMO Motion Benchmark 2 Explain energy conversions in moving objects and machines. Types of Energy There are three types of energy: Kinetic Potential Radiant Kinetic Energy is the energy of MOTION. Potential Energy is STORED energy. Radiant Energy is energy associated with waves from the electromagnetic spectrum (heat, radiation, light, etc.). Kinetic Energy Kinetic Energy is the energy of motion. Any object in motion has Kinetic Energy. The amount of Kinetic Energy depends on two factors: 1. The mass of the object. 2. The speed of the object. Which has more Kinetic Energy? A bowling ball rolling down the hallway at 1 m/s or a bowling ball rolling down the hallway at 5 m/s? A bowling ball rolling down the hallway at 1 m/s or a golf ball rolling down the hallway at 1 m/s? Potential Energy Potential Energy is stored energy. Energy can be stored in various forms. 1. Energy can be stored by raising an object above the ground (gravitational potential energy). 2. Energy can be stored by compressing or stretching a spring (elastic potential energy). 3. Energy can be stored in the chemical bonds of a compound (chemical potential energy). 4. Energy can be stored in the form of electricity (electrical potential energy). Energy can be released from each of these forms into Kinetic Energy! Radiant Energy Radiant Energy is energy associated with waves from the electromagnetic spectrum (heat, radiation, light, etc.). There are various forms. 1. Heat from any source (the sun, fire, etc.) is infrared waves. 2. Visible Light Energy can be stored by compressing or stretching a spring (elastic potential energy). 3. Gamma Rays and X-Rays are high energy electromagnetic waves. Energy Transformations Energy is never created or destroyed; it is only converted from one form to another. This is called the LAW OF CONCERVATION OF ENERGY. Gravitational Potential Ball rolling down a hill Elastic Potential Launching a water balloon Electrical Potential A light bulb lighting Radiant Kinetic Kinetic Chemical Potential Burning wood Radiant Real-world contexts Simple and complex machines roller coasters swings pendulums elevators automobiles fans motors Pendulums The TOTAL ENERGY IS CONSTANT Energy transformations are easily seen in pendulums. A pendulum is released from a height H above its lowest height. Where is it moving the fastest? Is it ever stopped? How high will it rise on the opposite side? Describe the energy conversions as it swings. H Roller Coasters Energy transformations are easily seen in roller coasters. A roller coaster car travels from the high points to the low points. Where is it moving the fastest? Where is it moving the slowest Describe the energy conversions as it rolls. The TOTAL ENERGY IS CONSTANT Friction Friction occurs when two objects rub against one another. Friction generates heat (radiant energy) and gives it off to the surroundings. Therefore the height of a real pendulum will decrease over time, the gravitational potential and kinetic energies are being converted to radiant energy. Web Exploration http://physics.weber.edu/amiri/director/DCRfiles/Energy/bungee4s.dcr http://www.phy.ntnu.edu.tw/java/Pendulum/Pendulum.html http://www.walter-fendt.de/ph11e/springpendulum.htm http://www.funderstanding.com/k12/coaster/