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Atomic number – number of protons; identifies the element Atomic mass – number of protons plus the number of neutrons in the nucleus of atom (protons + neutrons) Protons = positive charge Neutrons = no charge Electrons = negative charge You can know the number of electrons because in neutral atom the number of electrons is the same as the number of protons
If the atomic number for arsenic is 33 and the atomic mass is 75 then:
How many protons does arsenic have?
How many neutrons can you find in the nucleus of the arsenic-75?
How many electrons in arsenic’s electron cloud?
33
42
33
Fusion or Fission
Fusion = joining together two nuclei; example the Sun Fission = splitting apart of atoms; such as in nuclear reactor plants
Fission
Phase change – occur as a result of energy being added or taken away from matter
As temperature rises, matter moves to a more rapid state
F = ma
If F = 100 N and m = 50 kg;
what is the dog’s acceleration?
100 N = 50kg (a) 100 N /50kg = a 2 m/s2 = a
Newton’s First Law of Motion
An object at rest will remain at rest and an object in motion will remain in motion unless acted on by an outside net force; objects tend to keep doing what they are doing
Newton’s Second Law of Motion
change of velocity, or
acceleration, is related to the mass of
the body and the force applied
Work = Force x Distance
If the blonde boy does not make the rock move is he doing any work?
NO…you need distance
More Physics
• Speed = distance/time
• Velocity is speed in a particular direction
• Acceleration is change in velocity/time elapsed
Electromagnetic Spectrum
Long wavelength = low frequency Short wavelength = high frequency
Electromagnetic waves do not need to travel through a medium
Speed of Sound – depends on the medium it passes through
Sound cannot pass through a vacuum – no molecules present
Sound waves travel faster at higher temperatures and density
Sound travels faster through a solid and slower through a gas
Interference – when two waves meet while traveling through the same medium
(a) Constructive (b) Destructive
Electricity
•Electricity – flow of electrons •Voltage – amount of energy available to move electrons •Current – rate of electron flow •Resistance – hindering electron flow