physics notes

Grade 9-10 Physics Notes

Unit 1 - Motion

Distance and Displacement

• Distance: Length of the total path traveled by an object.

  • S.I Unit: Meters (m).

  • Distance can never be negative or zero.

  • Scalar Quantity: Only provides magnitude.

• Displacement: Shortest distance from the initial position of an object to its final position.

  • S.I Unit: Meters (m).

  • Calculated as: (X_f - X_i) (Final position - Initial position).

  • Vector Quantity: Includes both magnitude and direction.

  • Displacement can be zero or negative.

    • Example: Jogging back to the starting position results in zero displacement with a distance of 5 km.

    • Example: Moving on a number line: 2m right then 5m left results in -3m displacement.

Speed, Velocity, and Acceleration

• Speed: Measure of how fast an object is moving; distance traveled per unit time.

  • S.I Unit: Meters per second (m/s).

  • Scalar Quantity: Only indicates magnitude.

  • Formula: Average speed = distance traveled / time.

• Velocity: Speed of an object in a specific direction.

  • S.I Unit: Meters per second (m/s).

  • Vector Quantity: Indicates both magnitude and direction.

  • Formula: Velocity = displacement / time.

• Acceleration: Rate of change of velocity per unit time.

  • S.I Unit: Meters per second squared (m/s²).

  • Vector Quantity: Involves change in velocity.

  • Formula: Acceleration = (final velocity - initial velocity) / time.

  • Deceleration/Negarive acceleration occurs when velocity decreases.

Motion Graphs

• Two types of motion graphs:

  1. Distance/Displacement-Time Graph: Time on x-axis; distance/displacement on y-axis.

     • Slope indicates speed (distance) or velocity (displacement).

  2. Speed/Velocity-Time Graph: Time on x-axis; speed/velocity on y-axis.

     • Slope indicates acceleration; area under graph represents distance traveled.

Unit 2 - Heat and Energy

States and Properties of Matter

• States of Matter: Solid, Liquid, Gas.

  • Solids: Fixed volume/shape, strong intermolecular forces, low kinetic energy (particles vibrate).

  • Liquids: Fixed volume, no fixed shape, weaker intermolecular forces, moderate density and kinetic energy (particles flow).

  • Gases: No fixed volume/shape, very weak intermolecular forces, high kinetic energy (particles move freely).

Temperature and Heat Transfer

• Temperature: Measure of average kinetic energy of particles.

• Heat: Transfer of thermal energy between two objects at different temperatures.

• Thermal Equilibrium: Achieved when two bodies reach the same temperature with no net heat transfer.

Specific Heat Capacity

• Specific Heat: Amount of heat required to raise the temperature of 1 kg of a substance by 1°C.

  • Formula: (Q = mc riangle T) where Q is heat, m is mass, c is specific heat capacity, and ( riangle T) is temperature change.

• Latent Heat: Energy required for phase change without temperature change.

  • Latent Heat of Fusion: Solid to liquid.

  • Latent Heat of Vaporization: Liquid to gas.

Unit 3 - Waves

Wave Basics

• Definition: A disturbance that travels through a medium transferring energy without transferring matter.

• Types of Waves:

  • Mechanical Waves: Require a medium (e.g., sound).

  • Non-Mechanical Waves: Do not require a medium (e.g., light).

Properties of Waves

• Amplitude: Height of a wave from equilibrium position.

• Wavelength: Distance between two corresponding points on consecutive waves.

• Frequency: Number of waves passing a point in one second (S.I Unit: Hertz, Hz).

  • Formula: (f = 1/T) where T is time period.

  • Wave Speed: Formula: (V = f \lambda) where (V) is speed, (f) is frequency, (\lambda) is wavelength.

Sound Waves

• Propagate through air by oscillation of air particles; require a medium to travel.

• Measured speed in air = 343 m/s.

Unit 4 - Electricity

Basic Concepts

• Electric Charge: Property causing attraction/repulsion in particles; measured in Coulombs (C).

  • Types: Positive (protons) and negative (electrons).

• Current (I): Flow of charged particles; measured in Amperes (A).

  • Formula: (I = Q/t) where Q is charge and t is time.

• Voltage (V): Potential difference between two points; the "pressure" in the electrical circuit that pushes current.

  • Formula: (V = I \times R) where R is resistance.

Key Definitions and Laws

• Ohm's Law: Current is directly proportional to voltage and inversely proportional to resistance.

• Power (P): Rate at which electrical energy is produced; measured in Watts (W).

  • Formula: (P = V \times I)

• Series Circuit: All components in a single path.

• Parallel Circuit: Multiple paths for current to flow.

Unit 5 - Forces Definition of Force: A push or pull acting on an object, measured in Newtons (N). Types of Forces:

• Contact Forces: Forces that require physical contact (e.g., friction, tension).

• Non-Contact Forces: Forces that act at a distance (e.g., gravitational force, magnetic force). Newton's Laws of Motion:

1. First Law (Inertia): An object at rest stays at rest and an object in motion stays in motion unless acted upon by a net external force.

2. Second Law: Force equals mass times acceleration (F = ma). This law quantifies how the velocity of an object changes when it is subjected to an external force.

3. Third Law: For every action, there is an equal and opposite reaction. Friction: A force that opposes motion between two surfaces in contact. Types of friction:

• Static Friction: The friction that exists between a stationary object and the surface on which it's resting.

• Kinetic Friction: The friction between moving surfaces. Gravity: A force that attracts two bodies towards each other. On Earth's surface, the acceleration due to gravity (g) is approximately 9.81 m/s².