Physics (Shezan) 2

Chapter 1: Physical Quantities and Measurement

Physical Quantities

• Fundamental Quantities: Basic quantities such as length, mass, time, temperature, etc.

• Derived Quantities: Quantities derived from fundamental ones, including speed, volume, and density.

Units of Measurement

• Various systems of units:

  • CGS (centimeter, gram, second)

  • MKS (meter, kilogram, second)

  • SI Units: Standardized international system.

• Importance of standard units for uniformity in measurements.

Measurement Tools

• Length: Measured using a ruler, measuring tape, vernier caliper, or micrometer screw gauge.

• Mass: Measured using a beam balance or electronic balance.

• Time: Measured using stopwatches or clocks.

• Volume: Measured using measuring cylinders, beakers, or burettes.

Accuracy and Precision

• Accuracy: Closeness of a measurement to the true value.

• Precision: Consistency of repeated measurements.

• Importance of least count and significant figures for precise measurements.

Errors in Measurement

• Types of errors:

  • Systematic: Due to consistent factors affecting measurement.

  • Random: Unpredictable factors affecting measurement.

• Minimization of errors through improved techniques and tools.

Density

• Definition: Calculated as mass divided by volume.

• Significance of density in physics with practical applications.

Key Formulas

• Speed: Speed = Distance ÷ Time

• Density: Density = Mass ÷ Volume

• Volume of a cube: Volume = Side³

• Volume of a cylinder: Volume = π × Radius² × Height

Chapter 2: Force and Pressure

Key Concepts

1. Force:

   • A push or pull causing a change in motion or shape.

   • SI Unit: Newton (N).

2. Effects of Force:

   • Changes in motion or shape of an object.

3. Types of Forces:

   • Contact Forces:

     • Muscular Force

     • Frictional Force

   • Non-Contact Forces:

     • Gravitational Force

     • Magnetic Force

     • Electrostatic Force

4. Pressure:

   • Force applied per unit area.

   • SI Unit: Pascal (Pa).

Important Formulas

1. Force (F): Force = Mass × Acceleration

2. Pressure (P): Pressure = Force ÷ Area

3. Gravitational Force (Fg): Gravitational Force = Mass × Gravitational Acceleration

4. Friction: Depends on surface nature and the force pressing them together.

5. Pascal’s Principle: Pressure transmits equally in all directions in a fluid.

Applications

1. Pressure Changes:

   • Decrease area to increase pressure (e.g., knife blades).

   • Increase area to decrease pressure (e.g., wide tires).

2. Hydraulic Machines: Use Pascal’s Principle to multiply force (e.g., hydraulic brakes).

3. Atmospheric Pressure: Pressure exerted by the weight of air above.

Chapter 3: Sound

Key Points

• Definition of Sound: Energy produced by vibrating objects, traveling in waves.

• Production of Sound: Produced by vibrations (e.g., tuning fork, vocal cords).

• Propagation of Sound:

  • Requires a medium (solid, liquid, gas).

  • Cannot travel through a vacuum.

Characteristics of Sound Waves

• Frequency: Number of vibrations per second (Hertz, Hz).

• Amplitude: Maximum displacement of particles from rest position.

• Time Period: Time for one complete vibration.

• Speed: Distance traveled by wave per second (varies with medium).

Key Terms

• Wavelength (λ): Distance between consecutive compressions or rarefactions.

• Pitch: Determines the highness or lowness of sound.

• Loudness: Related to the sound wave's amplitude.

• Echo: Reflection of sound after hitting a hard surface.

Important Topics for Revision

• Speed of Sound: Fastest in solids, slower in liquids, slowest in gases.

• Reflection of Sound: Laws of reflection apply (angle of incidence = angle of reflection).

  • Uses: Echoes, SONAR.

• Human Ear Structure:

  • Parts: Outer ear, middle ear, inner ear.

  • Functions: Capturing sound waves, converting to electrical signals.

Main Concepts

• Noise vs. Music:

  • Noise: Irregular vibrations, unpleasant.

  • Music: Regular vibrations, pleasing.

• Range of Hearing:

  • Humans: 20 Hz to 20,000 Hz.

  • Infrasonic: Below 20 Hz, Ultrasonic: Above 20,000 Hz.

• Applications of Ultrasound:

  • Medical imaging (ultrasound scans), SONAR (Sound Navigation and Ranging).

Diagrams

• Include labeled diagrams for:

  • Waveforms of sound (compression and rarefaction).

  • Structure of the human ear.

  • Reflection of sound illustrating echo.