Sci long test (AGAIN..!! grr)

• Force is a push or pull on an object
• Types of Forces:

  • Contact
  • Noncontact
• Contact Forces:

  • Frictional Forces - any force that opposes the relative motion between objects or systems in contact ( ex. Wheels on a cart )
  • Applied Force - any force that opposes the relative motion between objects or systems in contact ( ex. Pushing or pulling the cart )
  • Normal Force - support force exerted on an object by a surface it is in contact with ( ex. A book on a table )
• Noncontact Forces:

  • Gravitational Force - the force of attraction between objects by virtue of their masses
  • Electromagnetic Force - the force responsible for the attraction and repulsion of charges
  • Nuclear Force - the force that holds the protons and neutrons within the nucleus
• Force causes motion
• Motion is described in terms of:

  • Speed  
  • Velocity
  • Acceleration
• Motion is the change in the position with respect to a reference point.
• Motion Descriptors

  • Distance -  length of the path covered by a moving object
  • Displacement - straight line distance between initial and final position of an object
  • Speed - the rate at which distance is covered over time
  • Velocity - the speed of an object in a particular direction
  • Acceleration 
• Physical Quantities

  • Scalar quantities - has magnitude (numerical size and unit only) ( ex. 5 meters long)
  • Vector quantities - has both magnitude and direction ( ex. 5 meters long East)
• Positive Acceleration - an increase in acceleration

  Negative Acceleration - an decrease in acceleration
• speed=distance/time

  distance=speed x time

  time=speed/distance
• velocity= displacement/time

  displacement= velocity x time

  time= displacement/velocity
• acceleration= final velocity - initial velocity/time

  final velocity=acceleration x time - initial velocity
• Waves: 

  • It is a disturbance that travels through a medium or a vacuum and carries energy. (Medium can be solid, liquid, and gas)
  • the energy can move from one location to another, yet the particles of matter in the medium return to their fixed position
• Waves can be categorized based on their ability to transfer energy in a vacuum.

  • Wave Pulse - single vibration
  • Wave Train - continuous source of vibration
• Characteristics of a Wave:

  • Frequency
  • Period
  • Wavelength
  • Velocity or speed
  • Amplitude
• Frequency f

  • High frequency and Low frequency 
  • the number of waves produced per unit of time
  • unit of frequency: hertz (Hz)
• Period T

  • the time taken for one complete cycle of the wave to pass a reference point
  • Expressed in units of time, usually seconds (s)
• Wavelength

  • the distance between any two successive points in a wave that are in phase with each other
• Speed v

  • the distance traveled by a wave per unit time
• Amplitude A

  • the maximum amount of displacement of a particle on a medium from its resting position
  • the greater the amplitude , the greater the energy carried by the wave
• Classification of waves according to its Nature

  • Mechanical
  • Electromagnetic
• According to the direction of vibration of particles:

  Longitudinal Waves

  Transverse waves
• Longitudinal Waves

  • the particles of the medium vibrate parallel to the direction of the wave propagation
  • composed of compressions (particles of the medium are closer together) and rarefactions (particles of the medium are apart
• Transverse Waves

  • the particles of the medium are vibrating perpendicularly to the direction of the wave propagation
  • made up of alternating hills and valleys
  • top of the hill (highest point) is called crest
  • bottom of the valley (lowest point is called trough
• Mechanical Waves

  • require a medium to propagate
  • Examples: ripples on water surface, sound waves, seismic waves
• Electromagnetic Waves

  • Can travel in a vacuum and in any medium
  • Examples: light, heat waves, radio waves, microwaves
• Sound: longitudinal waves produced by vibrating bodies
• We perceive sounds by our Human Larynx
• Pitch:

  • Used to describe the highness and lowness of sound
  • directly dependent on the frequency of the sound wave
  • Lower pitch sound with lower frequency
  • Higher pitch sound with higher frequency
• Loudness or Intensity

  • Energy delivered to a unit area of a surface per unit time. 
  • The SI unit of intensity is watt per square meter (W/m2)
  • loudness of sound is expressed in decibels (dB)
• Quality

  • (Timbre) Distinguishes sound from another sound of the same pitch and intensity
  • fundamental frequency: lowest frequency an instrument can produce
  • harmonics: multiples of fundamental frequency
• Sound is made when something vibrates and waves of energy, or vibrations, are sent into our ears. The sound waves bump into the air particles. The vibration is passed from one air particle to the next, which carries the sound along. When an object vibrates, it causes the surrounding air molecules to vibrate, initiating a chain reaction of sound wave vibrations throughout the medium.
• Echo: When a sound wave bounces off a surface and is reflected back to your ears, an echo is made.
• Echolocation: Bats use ultrasounds to monitor their surroundings. An object is identified when their ultrasound hits a certain object and bounces back.
• EFFECTS OF NOISE POLLUTION:

  • Impacts sleep habits
  • Hinders child development
  • Can cause psychological issues
• Harmonic: ​​a wave or signal whose frequency is an integral (whole number) multiple of the frequency of the same reference signal or wave