Energy

• Energy – ability to do work• 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

• Energy conversion – when a form of energy is changed to another form of energy

• 9 Types of Energy

1. Kinetic energy(KE= vm2/2)– energy in motion Faster an object is moving the greater the kinetic energy, also the more

mass an object has the greater the kinetic energy

2.Potential – energy due to the objects position (object could

move)

Gravitational potential energy – energy against the force of gravity—lifted objects have GPE

Formula KE= mv2/2

3. Mechanical energy – Has both kinetic + potential

• 4.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)

• 5.Chemical energy – energy of a compound that changes as its atoms are rearranged, a form of potential energy

• 6.Electrical energy – energy of moving electrons, a form of potential energy since motion only happens when object is connected to actual output

• 7.Sound energy – vibrating object transmit energy through matter (S-L-G)

• 8.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)

• 9.Nuclear energy – energy from the change in the nucleus of an atom

2 kinds of nuclear energy• 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 Energy– 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

• Energy conversions always create a certain amount of thermal energy for the transition to take place

Types of conversions

Chemical Energy• Photosynthesis – light energy to chemical

energy• 6CO2 + 6H2O + light energy → C6H12O6 + 6O2

• Cellular respiration – humans using chemical energy to kinetic energy

• C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP (energy)

• All chemical energy is potential energy.