Physical Science

1
Physical Science

• Chemistry and Physics
• study of matter and energy
• understanding the Universe
• improving the quality of life
• Science and Technology
• applying knowledge and information
• transportation (cars)
• issues related to matter and energy
• telecommunication (car phones)
• issues related to matter and energy

2
Physics

• Motion
• Newtons Laws
• Work
• Machines
• Energy
• Sound Waves
• Light Waves
• Electricity and Magnetism

3
Motion

• Position, velocity, and acceleration
• time dependence
• metric units m and m/s and m/s2
• velocity and speed are not exactly the same
• speed distance/time (10 m/s)
• velocity speed and a direction (10 m/s south)
• constant velocity means that speed and direction
  do not change
• acceleration
• change in velocity with respect to time
• a 0 if speed and direction do not change
• acceleration occurs when there is a change in
  speed
• acceleration occurs when there is a change
  direction
• circular motion at constant speed accelerated
  motion
• acceleration due to gravity
• objects speed up as they fall
• at surface of the Earth g 9.8 m/s2

4
Newtons Laws of Motion

• the action of forces determine the motion of
  objects
• a force is a push or a pull (contact and
  non-contact)
• metric unit of force is the Newton (N)
• weight the force acting on an object due to
  gravity
• mass and weight are not the same
• metric unit of weight is the newton (N)
• metric unit of mass is the kilogram (kg)
• w mg (where g is the acceleration due to
  gravity)
• on Earth g 9.8 m/s2
• on moon g 1.6 m/s2
• if my mass is 100 kg what is my weight on the
  Earth and on the moon?
• friction a force that opposes motion
• air resistance
• moving through air versus moving through water
• sliding versus rolling friction
• friction also enables motion

5
Newtons Laws of Motion

• Newtons first law of motion
• law of inertia
• no change in motion when forces are balanced
• object is at rest
• object motion is one of constant velocity
• in either case a 0
• Newtons second law of motion
• motion changes when forces are not balanced
• F ma (force mass x acceleration)
• object is accelerating (velocity is changing)
• Newtons third law of motion
• all forces occur in pairs
• for every force there is an equal but opposite
  force
• for every action there is a reaction
• momentum is defined as mass x velocity

6
Work

• definition of work involves a force acting over a
  distance
• forces can be interpreted as doing work when they
  act on objects
• positive work energizes an object
• negative work de-energizes an object
• W Fd (work force x distance)
• metric unit of work is the joule (J)
• rate of doing work is called power
• work per time
• metric unit of power is the watt (W)

7
Machines

• devices that make it easier to do work
• will not reduce the amount of work that must be
  done
• mechanical advantage
• usually reduces the amount of force that must be
  applied
• reduced force at the expense of an increased
  distance
• friction lowers the efficiency (effectiveness) of
  a machine
• six simple machines
• inclined plane
• lever
• wedge
• wheel and axle
• pulley
• screw

8
Energy

• forms of energy
• thermal
• solar
• electric
• chemical
• mechanical
• nuclear
• energy and work are related (both have units of
  joules)
• conservation of energy
• all energy must be accounted for
• energy cannot be created or destroyed
• energy can be converted
• chemical to electrical to mechanical (battery
  operated car)
• conversion is not 100

9
Mechanical Energy

• kinetic energy energy associated with motion
• KE 0.5mv2
• no motion then KE 0
• potential energy energy associated with
  position
• gravitational PE mgh
• h 0 then PE 0
• sometimes mechanical energy is conserved
• motion of a pendulum (PE gt KE gt PE)
• pendulum eventually does what?
• friction is an energy thief
• as an object falls what is happening to its PE
  and KE?

10
Heat Energy

• heat is thermal energy on the move
• what happens to the temperature of an object as
  it gains heat?
• what happens to the temperature of an object as
  it loses heat?
• temperature is indicative of the average KE of
  the atoms/molecules
• the higher the temperature the greater the motion
  at a molecular level
• transfer of heat occurs by one of three different
  methods
• conduction direct contact
• touch a hot pan
• convection moving fluids (convection currents)
• hold your hand in front of a hair dryer
• radiation infrared
• stand outside in the sunlight
• heat naturally flows from hot to cold objects
  (not the reverse)
• insulators restrict the flow of heat (styrofoam
  cup)
• conductors promote the flow of heat (metal pan)

11
Waves

• vibrations that travel through matter or space
• transverse waves vibration is perpendicular to
  direction of travel
• longitudinal waves vibration is parallel to
  direction of travel
• waves carry energy but not matter
• mechanical waves can only travel through matter
• sound is a mechanical wave
• electromagnetic waves can travel with or without
  matter present
• light is an electromagnetic wave
• wave frequency number of vibrations per second
• metric unit is the hertz (Hz)
• wavelength crest-to-crest distance for a
  transverse wave
• wave speed frequency x wavelength (v fl)
• metric units of m/s
• affected by the medium that the wave travels
  through
• wave height (amplitude)
• related to the energy carried by the wave

12
Sound Waves

• longitudinal mechanical vibrations that we can
  sense via hearing
• frequency range of human hearing 20 to 20,000
  Hz
• sound pitch is related to the frequency of the
  wave
• sound waves can travel through solids, liquids,
  and gases
• speed of sound in air is about 340 m/s
• sound loudness is measured in decibels (dB)
• loudness is related to the amplitude of the wave
• musical instruments are designed to generate
  certain notes
• instrument geometry and material of construction
  factor into this

13
Light Waves

• transverse electromagnetic vibrations that we can
  sense via seeing
• visible portion of the electromagnetic (em)
  spectrum
• ROYGBIV
• red lower frequency light
• violet higher frequency light
• radio waves occur at the low frequency end of the
  em spectrum
• gamma rays occur at the high end of the em
  spectrum
• how is IR and UV radiation sensed by humans?
• speed of light is 300,000,000 m/s
• mirrors reflect light (bouncing of light at a
  boundary)
• image formation via mirrors
• lenses refract light (bending of light at a
  boundary)
• caused by a change in wave speed
• image formation via lenses
• convex and concave lenses (corrective lenses for
  vision problems)

14
Electricity

• Static electricity
• accumulation of a stationary charge on a surface
• due to the loss or gain of electrons at the
  surface of an insulator
• negatively charged surface if electrons are added
• positively charges surface if electrons are
  removed
• charge has units of coulombs (C)
• often caused by friction (rubbing)
• static electricity can cause items to stick
  together
• lighting (sudden discharge of static electricity)

15
Electricity

• Current electricity
• form of energy caused by the flow of electrons
• electricity can flow through conductors (metals)
• electricity cannot flow through insulators
  (plastics and ceramics)
• current is measured in amperes (A)
• charge per time (coulomb per second)
• circuit conductive pathway for the electric
  current
• series circuit end-to-end connection of
  conductors
• parallel circuit side-by-side connection of
  conductors
• Ohms law
• I V/R (current voltage divided by resistance)
  also V IR
• ammeter measures the current in a circuit
• battery voltage (electrical push) measured in
  volts (V)
• voltmeter measures the applied voltage in a
  circuit
• resistance measured in Ohms (W)
• resistance in a light bulb converts electrical
  energy into heat and light

16
Magnetism

• magnet metallic substance capable of attracting
  iron
• magnets have both a N pole and a S pole
• opposites attract and likes repel
• compass utilizes a magnet with respect to the
  Earths magnetic poles
• load stone a naturally occurring magnet
• electromagnet
• wire coil surrounding a metal core
• current through the wire causes the metal core to
  become magnetic
• electric motor
• converts electrical energy into mechanical energy
• involves a rotating wire coil surrounded by a
  magnet
• interaction of magnetic fields
• generator
• converts mechanical energy into electrical energy