Transcript Energy Conversion and Conservation
ENERGY CONVERSION AND CONSERVATION Review - Work Work is done when a force acts on an object in the direction the object moves. Work = Force x Distance W=FxD The joule (J) is the SI unit of work. Review - Power Power is the rate of doing work. Power = Work / Time P = W/t The SI unit of power is the watt (W) Review - Energy Work causes a change in the energy of a system. The two main types of energy are: Kinetic potential Review – Kinetic Energy Kinetic energy depends on motion and is measured in joules (J). KE = ½ mv2 v = velocity Review – Potential Energy Gravitational Potential Energy depends on height and is measured in joules (J). PE = mgh h = height g = acceleration due to gravity 9.8m/s2 Energy Conversion Energy can be converted from one form to another. The process of changing energy from one form to another is energy conversion. EX: Rubbing hands – kinetic energy to thermal energy. Conservation of Energy When energy changes from one form to another, the total energy remains unchanged. The law of conservation of energy states that energy cannot be created or destroyed. Energy Conversions The gravitational potential energy of an object is converted to the kinetic energy of motion as the object falls. EX: sky diving The kinetic energy of motion is converted to gravitational potential energy when an object is gaining height. EX: pole vaulting Energy Conversion in a Pendulum Energy Conversion Your beginning energy must equal your ending energy. This allows us to say that: (KE + PE)beginning = (KE + PE)end Which means you can set kinetic energy equal to potential energy.