# Matter & Energy Give me matter and motion, and I will construct the

## Presentation on theme: "Matter & Energy Give me matter and motion, and I will construct the"— Presentation transcript:

Matter & Energy Give me matter and motion, and I will construct the
universe.  Rene Descartes

ENERGY

It is important to realize that in physics today,
we have no knowledge of what energy is.  Richard P. Feynman

When is expenditure of energy required?
* tossing a ball * lifting a rock * launching a rocket When is expenditure of energy not required? * Rocket coasting through space

Satellite orbiting Earth requires no expenditure of energy. Expenditure of energy seems to require motion and force.

Some Varieties of Energy
* Kinetic Energy (Energy of Motion) > Thermal (heat) energy * Potential Energy (Stored Energy) > Elastic energy > Gravitational energy > Chemical energy > Electrical energy > Magnetic energy > Mass-energy * Radiative Energy

Kinetic Energy (KE) Mass (m) Speed (v) * KE  m * KE  v2

Heat & Temperature Higher Temp Lower Temp.

Conservation of Energy
Energy neither appears nor disappears. It may be converted from one kind to another, in which case the total amount of energy is unchanged.

Conservation of Energy + Mass
* Einstein: mass and energy are interchangeable mass (speed of light)2 * Total of mass + energy is what’s really conserved!

equivalent to detonating
0.1 kg mass  Energy equivalent to detonating 1 million tons TNT (1 ‘megaton’)

MATTER

ATOMS When it comes to atoms, language can be used
only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images. - J. Bronowski

Old Picture: Electrons orbit Nucleus: larger orbit more energy (‘Bohr Atom’)

New Picture Electron ‘cloud’

Probability of Finding Electron
Distance from Nucleus

In 3-D lowest energy next lowest energy or or next lowest energy

Hydrogen Energy Levels (1 electron) Excited States Ground State

Sodium Energy Levels (11 electrons)

 Atoms are usually neutral:
# protons = # electrons  Ions: atoms with one or more electrons added and/or removed  A chemical element consists of atoms with equal numbers of protons

 Isotopes consist of atoms of an element with a different number of neutrons
#protons #neutrons e.g.,Hydrogen 1 0 Deuterium Tritium  Atoms can bind together in molecules  A molecule is the smallest unit of a compound e.g., CO2, H2O, etc

Phases of Bulk Matter Solid Liquid Gas Plasma

Fully Ionized Plasma (Avg. Kinetic Energy) Temperature Gas Liquid Solid

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