Conservation of Energy Thermal Energy

Energy Elastic Energy There are a many forms of energy Electric Energy in an object from its compression or stretching Elastic band Electric The movement of electrons from 1 atom to another Batteries Thermal Disorganized movement of particles in any substance Fire Chemical Stored in the bonds of molecules Combustibles Wave Contained in a electromagnetic wave Radio Hydraulic Transported in the flow of water Waterfall Nuclear Energy stored in the center (nucleus) of an atom Sun

Energy Energy is defined as the capacity to do work of certain force There are 2 types of energy Potential (stored) Kinetic (working) Stored in different ways Renewable (solar, wind, geothermal) Nonrenewable (oil, fossil, coal)

Units Energy is expressed in Joules 1 J = 1 N x 1 m

Law of Conservation of Energy Energy may neither be created or destroyed, the total energy of a system remains constant Transfer: energy from 1 place to another Transform: energy in 1 form to another form

Energy Efficiency Energy efficiency is the percentage of energy consumed by a machine or system that was transformed into useful energy. p.72

Energy Output No energy is lost, but it can go unused Therefore Net Energy = Energy(Output) – Energy(Input) Efficiency = Input x 100 Output

Thermal Energy Disorganized movement of particles in a given substance Depends on the quantity of particles and the temperature of the substance

Quantity of Particles Particles Increase Particles Decrease Thermal Energy Increases Thermal Energy Decrease Temperature Temperature Increase Temperature Decrease

Heat Heat: the transfer of thermal energy between two areas of different temperatures Heat always passes from higher to lower Q = ∆Et Q = heat in J ∆Et = variation in temperature

Specific heat capacity The specific heat capacity corresponds to the amount of thermal energy required to raise the temperature of one gram of substance by one degree Celsius.

Formula Q= heat (J) m = mass (g) C = specific heat capacity (j/g C) Q = mc∆T Q= heat (J) m = mass (g) C = specific heat capacity (j/g C) ∆T = Tf – Ti (Tf= final temp; Ti = initial temp)

Sample questions Find the mass of water that released 1000J of energy by raising the temperature from 10oC to 18oC Determine the thermal energy of 0.5 kg of water heated from 20oC to 50oC