Physics - Combined Science FYE review

• • Heat is thermal energy which is moving from a warmer object to a cooler object.
  • It is shown by the movement of molecules and the distance between the molecules.
  • Temperature is the average of kinetic energy of the molecules
  • Gas state has the highest thermal energy since the molecules move faster and they are further apart.
• Solids

  Molecular movement: vibration in its place

  Liquids

  Molecular movement: slide each other in low speed

  Gases

  Molecular movement: to all directions in high speed
• CONDUCTION

  • Heat conduction or thermal conduction is the transfer of thermal energy through matter. It works by vibration between molecules of solid and movement of free electrons.
  • It is by direct contact.
• CONVECTION

  • Convection is the movement of molecules within fluids ( a liquid or a gas); the warm fluid rises and cooler fluids flow in to replace it. This creates a circular flow called convection current.
• RADIATION

  • The transfer of energy by electromagnetic waves.
  • Radiation does not require matter to transfer thermal energy.
• HEAT CONDUCTORS AND INSULATORS

  • A conductor is an object that can conduct heat well. An object will become a better conductor in black colour or dark colours since it absorbs most of the light.
  • An insulator is an object that conducts heat poorly. An object will become a better insulator in white colour of light colours since it reflects most of the light
• Melting point is the temperature when solid becomes liquid since the bond between molecules are weaken (force between molecules is reduced).

  Boiling point is the temperature when liquid becomes gas since the bond between molecules are broken (force between molecules is reduced some more).
• Melting/boiling Graph

  A) Gas

  B) Boiling point

  C) Liquid

  D) Melting point

  E) Solid

  
• Reverse process: cooling

  A) Gas

  B) Condensing

  C) Liquid

  D) Freezing

  E) Solid

  
• Thermal

  • Temperature increases depends on the mass , the heat transferred and the conductivity of the substance itself. Conductors increases its temperature faster while insulator increases its temperature in a long time.
• Evaporation and boiling has a similiraty in which molecules loses itself from liquid phase into gas phase when those molecules have enough energy to break the bonds between molecules. The result is the decreament of temperature (evaporation especially) this is due to the molecules that keep on moving at all temperatures (except 0 K or absolute temperature).
• Pressure is proportional to Temperature

  Volume is proportional to Temperature

  Pressure is inversely proportional to Volume
• Mass (in kg)

  • Mass is a measurement of mass and amount of particles (atom) in an object/substance. It is measured with mass balance.
  • It does not concern with the state of the object or place of the object.
  • Mass of 1 kg of steel will be the same even when it is in liquid,solid or gas state, or when it is at the moon.
• Weight (N)

  • Weight is the force acting on an object/substance because of gravity at its place. It is measured with force meter.
  • Weigth of an object does not change when it changes its state. Weight changes when object change its place to a different gravity.

  Weight(w) = mass x gravity
• Density

  • is the ratio of the mass of an object to its volume.
  • is a quantity that represents the mass of an object in 1 unit of volume.
  • Density(ρ) = mass(m)/ volume(V) in g/mL or g/cm3 or kg/m3(SI)
• • Ice floats in water because the density of ice is less than the density of water.
  • Aluminum sinks because its density is greater than the density of water.
• Force is an influence that can change the shape, size or movement of an object.

  Change of length and shape

  Change of movement or direction
• Types of Forces

  • Intentional Force (pushing/pulling,F)

  Made by human/machine which has the same direction as the direction of the pushing/pulling.

  • Gravitational Force (weight,w)

  Direction: from center of mass downward.

  • Frictional force (f)

  It hinders the movement which is directed opposite to the movement on the surface which causes heat. Air resistance is a form of friction by air molecules.

  • Tension (T)

  Force from string or rope which is directed from an object to the string/rope.

  • Normal (N/R)

  Reaction force from the surface to the object which is directed from the surface upward.
• Types of Forces

  • Rotational Force (centripetal Force, Fc)

  Centripetal Force which causes a circular motion. It is a force that goes to the middle of the circular path. The bigger the force the smaller the circular path. The bigger the velocity of object the bigger the force.

  • Resultant Force (R)

  Resultant force is the sum of all forces that work on an object or a system.
• Newton’s Laws

  1st: object will remain at rest OR at constant speed unless there is an unbalanced force.

  R=resultant force= 0

  2nd : acceleration of an object is directly proportional to the force that causes its motion.

  R=resultant force= m.a

  3rd: in every action force there is a reaction force with the same magnitude but to opposite direction.

  Freaction = -Faction
• What is frequency ? Amount of full waves/oscillations in

  one second

  What is period ? Amount of time to make one full wave or

  one oscillation. Period = 1/ frequency

  What is wavelength? Length of one oscillation or one full

  wave.

  What is Amplitude ? the biggest distance of disturbance

  from middle line
• Wave speed is the product of wavelength and frequency or distance travelled by wave in one second. ( in m/s or m.s-1)

  Wave speed = wavelength x frequency,

  v = λ x f

  Wave Speed = Wavelength/ Period ,

  v = λ/T

  since frequency = 1/ Period, f=1/T

  v = ƒ λ
• Reflection is the bending of light in which makes the light return to its

  original medium. Reflection from rough surface is called diffuse

  reflection.
• Reflection of ligth off a flat surface follows law of reflection:

  Angle of incident (angle in) equals to angle of reflection(angle out)

  Angles are measured from normal line (perpendicular)
• Properties of Images in Plane Mirrors

  • Virtual image (inside the mirror)
  • Same size
  • Same distance as the distance of the object to the mirror laterally Inverted (left-right reversal)
• Base units are the units that produce all the units that are used

  in measurement. 7 base quantities and units: length (meter),

  mass(kg), time (second), Temperature (Kelvin), Electrical

  current (Ampere), amount of particles (mol), Intensity of light

  (Candela).
• Many units are derived from a combination of one, two or more

  of base units, these units are called Derived units. Example:

  m/s, m2, m3, m/s2.