Energy
Holt: Chapter 9
Fusion: Unit 4
Energy
• Energy conversion – when a form of energy is changed to another form of energy
• Energy – ability to do work (also measured in joules)
• Kinetic energy – energy in motion
• The faster an object is moving the greater the kinetic energy, also the more mass an object has the greater the kinetic energy
• Potential – energy due to the objects position (object could move)
• Gravitational potential energy – energy against the force of gravity—lifted objects have GPE
• Mechanical energy – Has both kinetic + potential
• Law of conservation of energy – energy cannot be created or destroyed but can be changed from one form to another
• Energy efficiency – the amount of useful energy after a conversion – the more efficient the more energy that can be used
• Ex: shape of car, shape of plane, houses, windows
• Thermal energy – all the kinetic energy due to motion of particles that make up the object (faster the particles move the greater the thermal energy)
• Chemical energy – energy of a compound that changes as its atoms are rearranged, a form of potential energy
• Electrical energy – energy of moving electrons, a form of potential energy since motion only happens when object is connected to actual output
• Sound energy – vibrating object transmit energy through matter (S-L-G)
• Light energy – vibration of electrically charged particles, doesn’t need to be carried through matter, can travel in a vacuum (area with no matter-- SPACE)
Nuclear Energy
• Nuclear energy – energy from the change in the nucleus of an atom
• Nuclear fusion – the joining of atoms (H)
• Ex: when hydrogen is fused together at very high speeds to form helium (stars are nuclear reactors on a massive scale), the process releases tremendous amounts of energy
• Nuclear fission – the splitting of an atom
• Ex: when uranium is split, the potential energy in the nucleus is given off and used in nuclear power plants to generate electrical energy
• Electrical – can be changed into thermal,
sound, light and kinetic energy (most common energy used)
• Energy conversions allow us to maintain our daily lives through machines
• Conversion of energy always creates a certain amount of thermal energy for the transition to take place
• Chemcial:
• Photosynthesis – light energy to chemical energy
• 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
• Cellular respiration – humans turning food (chemicals) into energy
• C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP (energy)