energy and its forms (15.1). energy : the ability to do work work: the transfer of energy - energy...
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ENERGY and its FORMS (15.1)
energy : the ability to do work
work: the transfer of energy
- energy is transferred by a force moving an object through a distance…
both are measured in joules (J)1J = 1N-m (newton-meter)
kinetic energy: energy of motion
the kinetic energy of any moving object depends on mass and speed
kinetic energyKE = 1/2mv2
potential energy: energy that is stored as a result of position or shapeenergy with the potential to do work
gravitational potential energy: potential energy that depends on an object’s height
an objects gravitational potential energydepends on its mass, height and the acceleration due to gravity
potential energy (PE) = mgh
elastic potential energy – the potential energy of an object that is stretched or compressed
Forms of Energy…
mechanical energy: energy associated with motion and the position of everyday objects
thermal energy: the total potential and kinetic energy of all the microscopic particles in an object
chemical energy: the energy stored in chemical bonds in compounds
electrical energy: energy associated with electric charges
electromagnetic energy: form of energy that travels through space in the form of waves
nuclear energy: energy stored in atomic nuclei
the nucleus of an atom is held together by strong and weak nuclear forces which can store an enormous amount of energy
Chapter 15.2Energy Conversion and Conservation
energy conversion: energy can be converted from one form to another
law of conservation of energy states that energy cannot be created or destroyed – it converted from one form to another
the gravitational potential
energy of an object is converted to
the kinetic energy of motion as the
object falls (avalanche)
Energy Calculations
• when friction is small enough to be ignored, and no mechanical energy is added to the system, then the system’s mechanical energy does not change
• mechanical energy = KE + PE
conservation of mechanical energy
(KE + PE) beginning = (KE + PE) end
Energy and Mass
in Einstein’s equation (E=mc2 ) – energy and mass are equivalent and can be converted into each otherE (energy) = m(mass) x c (speed of light)2
- energy released as matter is destroyed and matter can be created from energy
Chapter 15.3ENERGY RESOURCES non-renewable energy sourcesexist in limited quantities – once used, cannot be replenished…oil, natural gas, coal and uranium
fossil fuels (oil, natural gas and coal) – formed underground from the remains of once-living organisms – account for the majority of the world’s energy – not evenly distributed throughout the world
renewable energy sources can be replaced in a relatively short period of time – most originate directly / indirectly from the sun –
hydroelectric, solar, geothermal, wind, biomass, nuclear fusion
Conserving energy resources…
energy resources can be conserved by reducing energy needs and by increasing the efficiency of energy use
energy conservation: finding ways to use less energy or to use energy more efficiently