Physics 9

• Speed is calculated as Distance divided by Time
• Average speed is the Total Distance taken divided by the Total time travelled
• Distance is the total path length covered by an object from the initial position to the final position
• Displacement is the shortest distance between the initial and the final position
• Velocity is calculated as Displacement divided by Time
• Average Velocity is the Total displacement divided by the Total Time Taken
• Acceleration is calculated as the change in velocity divided by time (a = v - u / t)
• The SI unit for acceleration is meters per second squared (m/s^2)
• Gravitational acceleration is the change of velocity due to gravity and is represented by g = GM/R^2 or approximately 9.8 m/s^2 on Earth
• Equations of motion for constant gravitational acceleration:

  1. v = u + gt
  2. h = ut + 1/2gt^2
• Inertia increases with mass
• Mass multiplied by Gravitational acceleration equals Weight
• To convert weight from Earth to Moon, multiply by 1/6; from Moon to Earth, divide by 1/6
• To convert mass to weight, multiply by 9.8; to convert weight to mass, divide by 9.8
• The SI unit of pressure is the pascal (Pa)
• Pressure is directly proportional to force and thrust, where T = F = m x g
• Thrust (T) is calculated as the product of mass (m) and gravitational acceleration (g)
• To find area (a), multiply length (l) by breadth (b)
• The SI unit of wavelength is meters (m)
• Frequency's SI unit is Hertz (Hz)
• The SI unit of time period is seconds (s)
• Frequency is the number of oscillations per second
• Wavelength is the distance between two consecutive compressions (crest) or two consecutive refactions (trough) in a wave
• The magnitude of maximum displacement on either side of the main position in a wave is called the amplitude
• Pitch is the sensation of frequency of an emitted sound, where high pitch corresponds to higher frequency making a shrill sound, and low pitch indicates a lower frequency causing a hoarse sound
• Loudness of a sound wave depends on its amplitude; louder sounds have more amplitude
• Intensity of a sound is the sound energy transferred per unit area and per unit time perpendicular to the direction of motion
• Intensity is a physical quantity and its SI unit is Joules per second per meter squared (J/s/m^2)
• Sound waves can travel through solids, liquids, or gases.
• The speed of sound is approximately 340 m/s at room temperature.
• In solids, sound travels by vibrations that are transmitted from one atom to another along the length of the solid material.
• In solids, the particles vibrate around fixed positions.
• In liquids, sound travels as longitudinal waves with particles oscillating back and forth parallel to the direction of propagation.
• In gases, sound travels as both longitudinal and transverse waves with particles oscillating back and forth parallel to the direction of propagation.
• Sound = lamda x 1/time

  sound =lamda x nev
• The persistence of sound in an auditorium is result of repeater reflections sound and is called reverbevation.

  The audile range of hhearing for an average human begings is in the frequency range of 20Hz-20kHz

  Echo = 2d/t

  d=vt/2=17m at least 17 meter
• 1. SI unit for voltage, represented by the letter v
• 1. Represents the mass number
• 1. Represents the elementary charge carried by a single proton
• 1. Represents the atomic number, the charge number of an atomic nucleus