Energy Energy is the capacity to do work or produce heat or change The study of energy and its transformations is known as thermodynamics Objects, from baseballs to molecules, can produce energy

Units of Energy The unit for energy is the joule (“jool”) A joule is not a large amount of energy and is often expressed in kJ A mass of 2 kg moving at a speed of 1 m / s possesses a kinetic energy of 1 Joule (1 J) Energy changes in chemical reactions will sometimes be expressed in calories (cal) 1 calorie = 4.184 J EXACTLY and is the amount of energy needed to raise 1 g of water 10 C The specific heat of an object is the amount of energy it takes to raise the temperature of the substance one degree Celsius…the greater the specific heat, the more energy required to raise its temperature

Energy: Mechanical-(Kinetic and Potential) Kinetic energy is energy in motion Kinetic energy increases as the speed of an object increases…also increases with increasing mass Potential energy is stored energy due to the position of an object Potential energy can be gravitational, chemical, nuclear, or elastic Potential energy can be converted into kinetic energy Mechanical energy = Potential energy + Kinetic energy

energy Chemical energy of substances is due to the potential energy stored in the arrangements of their atoms…coal, gasoline, hydrogen Thermal energy the total amount of energy from the movement of particles in matter; the atoms in matter are always moving; the more motion, the more thermal energy; heat and thermal energy are not the same…heat is transferred, thermal energy is a quantity Mechanical Energy: energy that moves objects; mechanical energy is the sum of kinetic and potential energy to do work Sound Energy vibrations of states of matter Electromagnetic Energy: Energy that can travel through empty space in waves…light falls under this Nuclear Energy: energy that has its source in the nucleus of an atom…can result from fusion or fission **Other forms of energy, like electricity, will fall under these**

Law of Conservation of Energy Like matter, Energy can neither be created nor destroyed, it can only change form…This is the LAW OF CONSERVATION OF ENERGY Energy is conserved, it changes form!!! Energy will be transferred from high to low No energy transfer is 100% efficient

Renewable vs. Non renewable To Flipchart Non-renewable energy sources cannot be replenished (made again) in a short period of time. Examples include: coal, petroleum, natural gas, propane, nuclear, and oil Renewable energy sources can be replenished naturally in a relatively short period of time. Examples include: hydropower, geothermal, wind, solar, and biomass Secondary energy sources are those that come from the conversion of other sources of energy, like coal, natural gas, oil, nuclear power and other natural sources, which are called primary sources.

Energy Energy is transferred in two general ways Work is energy used to cause an object to move against a force; work = force x distance moved W = fd; units are Joules Heat is the energy transferred from a hotter object to a colder one; thermal energy and heat are not the same! The transfer of heat results in an increase in thermal energy! Energy Efficiency is a measurement of how much energy is converted into a desirable form and how much is released into the surroundings as heat

TEMPERATURE AND PARTICLE MOVEMENT The Kinetic theory of matter states that ALL of the molecules that make up matter are constantly in motion Remember how particles behave in the states of matter!!! Temperature is a measure of the average kinetic energy of all molecules in an object. If something is said to have a high temp. that means its molecules are moving fast and have a HIGH average kinetic energy When something warms, its molecules speed up; when something cools, they slow down TEMPERATURE AND PARTICLE MOVEMENT

Direction of heat transfer Heat is the flow of energy from an object of high temperature to one of low temperature…when an object gives off heat, that means it is transferring energy!! Thermal energy is the total kinetic energy of molecules in an object…all the kinetic energy is added together! Thermal energy and temperature are different, why? When a system absorbs heat, it is said to be endothermic (endo = into) The release of heat is called an exothermic process (exo = out of) Heat flows out of the system and into the surroundings Direction of heat transfer

Energy / Heat transfer Heat can be transferred by conduction, radiation, and convection Conduction is the direct transfer of heat through touching of solid objects…objects that transfer heat easily are good conductors Convection is the transfer of energy through the movement of particles in a liquid or an gas Radiation is energy that travels as electromagnetic waves…it is unique in that it can travel through empty space

Temperature Scales oF = (9/5C) + 32 oC = 5/9(F – 32) The choice of a temperature scale is arbitrary, meaning it is not bound by rules A scientist who made especially good thermometers was Gabriel Fahrenheit (1686-1736)…he devised his own temperature scale Celsius, named after its inventor Anders Celsius (1701-1744) a Swedish Astronomer. It has the freezing point of water at sea level being 0 degrees Celsius, and the boiling point at sea level 100 degrees C Thermometers measure temp. by a variation of physical properties of the liquid inside…the liquid will expand with a rise in temperature (thermal expansion) oF = (9/5C) + 32 oC = 5/9(F – 32)

The Kelvin Scale K = oC + 273 SI unit for temperature is Kelvin Named after an English physicist and mathematician, Lord Kelvin (William Thomson) (1824-1907) The degree symbol (o) is not used However, one degree Kelvin is the same size as one degree Celsius The difference between Kelvin and Celsius is the location of the zero point (0C +273.15 K) 0 K, or absolute zero, is the point at which the motion of particles of matter, their kinetic energy, is gone!! The Kelvin Scale K = oC + 273