Energetic Forms and Changes

Kinetic Energy = Motion energy = “Work in Progress”

Potential Energy = stored energy = Stored Work Capability

Kinetic Energy

KE = ½ mv2

Kinetic Energy = ½ mass x (velocity)2

(Joules) (kg) (m/s)2

Gravitational Potential Energy

PEg = m g h

Potential Energy = mass x gravitational x height acceleration

(Joules) (kg) (m/s2) (m)

Potential Energy

What is the potential energy at the base of each step of the stairway?

Energy here PEg = mgh

Energy here KE=½ mv2

PEg (initial) = KE (final)

mgh = ½ mv2

Potential Energy “Types”

Gravitational

Elastic

Chemical

Electrical

Nuclear

Gravitational Potential EnergyEnergy stored due to an object’s position above the Earth’s surface; depends upon mass, height from earth’s surface

Elastic Potential EnergyEnergy stored by extension or compression

Chemical Potential Energy Energy stored in the form of a substance’s chemical bonds

Electrical Potential EnergyEnergy stored as the result of electrical charges (i.e., electrons)

Nuclear Potential EnergyEnergy stored in the nuclei of atoms

Light EnergyAn energy form defined as electromagnetic, having wave-like

characteristics

Sound EnergyAn energy form considered to be transferred as a mechanical

(compression) wave

Thermal EnergyRepresents the sum of the kinetic and potentialEnergy of all the particles in an object/system

Q = m ∆ T CThermal energy = mass x temp◦change x specific change heat Joules kg ◦C J/kg◦C

Temperature is the term that describes the total kinetic energy that results from the random motion of a system’s atoms and molecules

Heating Curve / Phase ChangesNote thermal energy use in changing kinetic energy of atoms/molecules, and in changing the nature of the attractions between these same particles (potential energy)

What might you hypothesize from the heating curve for the mixture shown above?

Lab / Industrial Uses of Fractional Distillation

ENERGY TRANSFERBY

1) Radiation 2) Conduction 3) Convection

1) Radiation – Energy transfer through space by visible light, ultraviolet light, and

other forms of electromagnetic radiation

2) Conduction – Energy transfer that occurs when mollecules collide; conduction takes place only when substances are in contact

3) Convection – energy transfer by the flow of a heated / warmer substance

(meterology – the upward movement of an air mass warmed by land or sea)