IGCSE Physics Summary Notes

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IGCSE Physics Summary Notes for Length and time

To measure length accurately, use appropriate instruments based on the object's size and precision required. The table below summarizes common instruments:

Instrument	Purpose	Accuracy
Ruler	Short lengths	± 1 mm
Vernier Calipers	External and internal dimensions, depths	± 0.1 mm
Micrometer Screw Gauge	Small thicknesses (e.g., wire, paper)	± 0.01 mm

Precautions:

• Align the scale parallel to the object being measured.
• Avoid parallax error by viewing the scale perpendicularly.
• For micrometer screw gauges, rotate the thimble gently until the object is held firmly without excessive force.

Measuring Time:

Time measurement devices include:

• Stopwatches for general timing
• Pendulum clocks for periodic motion

Calculation of Time Period:

Time period of a pendulum is calculated using the formula:

T = 2π √(l/g)

where:

• T = time period
• l = length of the pendulum
• g = acceleration due to gravity

IGCSE Physics Summary Notes Scalars and Vectors :

Scalars are quantities with only magnitude, no direction. Examples include distance, speed, time, and mass.

Vectors:

Vectors have both magnitude and direction. Examples include velocity, acceleration, force, and displacement.

To calculate the resultant of two vectors at right angles, use Pythagoras' theorem:

R = √(x² + y²)

IGCSE Physics Summary Notes Speed and Average Speed/ Velocity/Acceleration/Motion:

Speed: The distance traveled per unit time.

Average Speed: Total distance traveled divided by the total time taken.

Units: Meters per second (m/s) or kilometers per hour (km/h).

IGCSE Physics Summary Notes Distance-Time Graph:

• Steady Speed: Represented by a straight line with a constant slope.
• Zero Speed: Represented by a horizontal line.
• Accelerating Objects: Represented by a curved line with increasing steepness.
• Slope of the Graph: Indicates the speed of the object. A steeper slope means a higher speed.

IGCSE Physics Summary Notes Speed-Time Graph:

• Steady Speed: Represented by a horizontal line.
• Acceleration: Represented by an upward-sloping line.
• Deceleration: Represented by a downward-sloping line.
• Area Under the Graph: Indicates the distance traveled.

Between Speed and Velocity:

• Speed: Scalar quantity, only magnitude.
• Velocity: Vector quantity, includes both magnitude and direction.

IGCSE Physics Summary Notes Acceleration:

Uniform Acceleration: Acceleration remains constant over time.

Non-Uniform Acceleration: Acceleration changes over time.

Acceleration Due to Free Fall:

All objects fall with the same acceleration in the absence of air resistance. The value is approximately 9.8 m/s² on Earth.

Motion of a Parachutist:

A parachutist initially accelerates due to gravity. As air resistance increases, the acceleration decreases, and the parachutist reaches terminal velocity. When the parachute opens, air resistance increases significantly, causing rapid deceleration until a new, lower terminal velocity is reached.

IGCSE Physics Notes on Mass, Weight and Volume and Density:

IGCSE Physics Notes on Density:

Definition: Density is the mass per unit volume of a substance.

Formula: Density = Mass / Volume

Units: kg/m³, g/cm³

IGCSE Physics NOtes on Mass:

Definition: Mass is the amount of matter in an object.

Units: Kilograms (kg) or grams (g).

IGCSE Physics Notes on Weight:

Definition: Weight is the force exerted by gravity on an object.

Formula: Weight = Mass × Gravitational Field Strength

Units: Newtons (N).

Difference Between Mass and Weight:

• Mass: Scalar quantity, remains constant regardless of location.
• Weight: Vector quantity, varies with gravitational field strength.

IGCSE Physics Notes on Gravitational Field Strength:

The gravitational field strength is the force acting on a unit mass due to gravity.

Value on Earth: 9.8 N/kg

IGCSE Physics Notes on Volume:

Definition: Volume is the amount of space an object occupies.

Units: Cubic meters (m³) or cubic centimeters (cm³).

IGCSE Physics Notes on Volume of Regular solids [ Objects]:

Formulae for Volume of Regular Solids:

• Cube: Volume = Side³
• Rectangular Prism: Volume = Length × Width × Height
• Cylinder: Volume = π × Radius² × Height

IGCSE Physics Notes on Volume of Irregular Objects by Displacement Method:

Steps:

• Fill a measuring cylinder partially with water and record the initial volume.
• Submerge the object completely in the water and record the final volume.
• Calculate the volume of the object by subtracting the initial volume from the final volume.

Precautions:

• Avoid parallax error when reading the water level.
• Ensure the object is fully submerged and does not trap air bubbles.

Sources of Error:

• Air bubbles adhering to the object.
• Spillage of water during measurement.

IGCSE Physics Notes on Finding Density:

IGCSE Physics Notes on Finding Density of Regular Solids:

For Regular Solids: Measure dimensions, calculate volume using the appropriate formula, and use the density formula.

IGCSE Physics Notes on Finding Density of Irregular Solids:

For Irregular Solids: Use the displacement method to find volume and then calculate density.

For Liquids: Measure the mass of an empty container, then the mass of the container with the liquid. Find the mass of the liquid and divide by its volume.

Units: Ensure consistent units (e.g., convert cm³ to m³ if necessary: 1 cm³ = 1 × 10^-6 m³).

IGCSE Physics Notes on Density of Objects Less Dense than Water:

To measure the density of such objects (e.g., cork):

• Attach a sinker to submerge the object completely.
• Measure the combined volume using the displacement method.
• Subtract the sinker’s volume to find the object’s volume.

IGCSE Physics Notes on Floating and Sinking:

Objects float if their density is less than the fluid they are in. Objects sink if their density is greater than the fluid.

Example: Cork floats on water because its density is lower than water. Steel sinks because its density is higher.

Why Steel Sinks but Boats Float:

Steel sinks because its density is greater than water. However, a steel boat floats because its overall density (including the air inside) is less than water.

Force is a push or pull that can cause an object to change its motion, shape, or size.

Effects of Forces:

Forces can cause the following effects:

• Change the shape of an object.
• Change the motion of an object (speed up, slow down, or change direction).
• Change the size of an object.
• Bring an object to rest.

Extension-Load Graphs:

An extension-load graph shows how the length of an object, such as a spring, increases as a force (load) is applied. Initially, the graph is a straight line, indicating that the extension is proportional to the load.

Limit of Proportionality:

The limit of proportionality is the point on the graph beyond which the extension is no longer proportional to the load. Beyond this point, the object may not return to its original shape when the force is removed.

Hooke's Law:

Statement: The extension of a spring is directly proportional to the applied force, provided the limit of proportionality is not exceeded.

Formula: F = kx

• F: Force (N)
• k: Spring constant (N/m)
• x: Extension (m)

Definition of Extension:

Extension is the increase in length of an object when a force is applied. For example, if a spring has an original length of 10 cm and stretches to 12 cm when a load is applied, the extension is 2 cm.

Resultant Force:

Definition: The resultant force is the single force that has the same effect as all the forces acting on an object combined.

Zero Resultant Force:

If the resultant force on an object is zero, the object remains at rest or continues to move at a constant velocity. For example, a stationary book on a table has zero resultant force.

Non-Zero Resultant Force:

If the resultant force is not zero, the object accelerates in the direction of the resultant force. For example, a car accelerating when the engine force is greater than friction.

Newton's Second Law:

Statement: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Formula: F = ma

• F: Force (N)
• m: Mass (kg)
• a: Acceleration (m/s²)

Motion in a Circular Path Due to Perpendicular Force:

When an object moves in a circular path, it experiences a centripetal force that acts perpendicular to its motion. This force constantly changes the direction of the object, keeping it in circular motion. For example, a satellite orbiting Earth is kept in its path by the gravitational force acting as the centripetal force.

Meaning of Turning Effect:

The turning effect of a force is the rotational effect produced when a force is applied to a pivoted object. It determines how effectively a force can cause an object to rotate around a fixed point.

Alternate Word for Turning Effect:

The turning effect of a force is also known as the moment of force.

Formula for Moment of Force:

Moment = Force × Perpendicular Distance from the Pivot

Units:

• Force: Newtons (N)
• Distance: Meters (m)
• Moment: Newton-meters (Nm)

Clockwise and Anticlockwise Moments:

• Clockwise Moment: A moment that causes an object to rotate in a clockwise direction. For example, opening a door by pushing its handle in the clockwise direction.
• Anticlockwise Moment: A moment that causes an object to rotate in an anticlockwise direction. For example, tightening a bolt with a spanner in the anticlockwise direction.

Fulcrum:

The fulcrum is the fixed pivot point around which an object rotates. It is the point of support for a lever. For example, in a seesaw, the central pivot acts as the fulcrum.

Conditions for Equilibrium:

• The sum of clockwise moments must equal the sum of anticlockwise moments.
• The resultant force acting on the object must be zero.

Principle of Moments:

The principle of moments states that for an object to be in equilibrium, the sum of the clockwise moments about a pivot must be equal to the sum of the anticlockwise moments about the same pivot.

Mathematically:

Σ Clockwise Moments = Σ Anticlockwise Moments

Uses of Moment of Force:

• Opening and closing doors or gates.
• Using levers to lift heavy objects (e.g., crowbars).
• Operating tools like spanners and wrenches.
• Balancing objects on a pivot, such as in a weighing scale.

IGCSE Physics Notes Momentum and Impulse:

Define Momentum:

Definition: Momentum is defined as the product of an object's mass and velocity.

Formula: Momentum (p) = Mass (m) × Velocity (v)

Units: Kilogram meter per second (kg m/s).

Define Impulse:

Definition: Impulse is defined the product of force and the time duration over which the force acts. It is also equal to the change in momentum of an object.

Formula: Impulse (J) = Force (F) × Time (t)

Units: Newton-second (N s).

Relationship with Momentum: Impulse equals the change in momentum: J = Δp.

Principle of Conservation of Momentum:

The principle of conservation of momentum states that in a closed system with no external forces, the total momentum before and after an interaction remains constant.

Formula: m₁v₁ + m₂v₂ = m₁v_1' + m₂v_2'

• m₁ and m₂: Masses of two objects
• v₁ and v₂: Initial velocities
• v_1' and v_2': Final velocities

Examples of Momentum:

• Collision Between Two Cars: When two cars collide, the momentum of the system (both cars) before and after the collision remains the same, assuming no external forces like friction.
• Rocket Propulsion: The momentum of the exhaust gases is equal and opposite to the momentum of the rocket, demonstrating conservation of momentum.

Word Problem Example:

Problem: A 1,500 kg car moving at 20 m/s collides with a stationary 1,000 kg car. After the collision, the two cars stick together and move as one unit. Find their final velocity.

Solution:

• Initial Momentum: (1500 kg × 20 m/s) + (1000 kg × 0 m/s) = 30,000 kg m/s
• Final Momentum: (1500 kg + 1000 kg) × v
• Using conservation of momentum: 30,000 = 2500 × v
• Final Velocity: v = 12 m/s

Motion in Terms of Impulse:

Impulse is crucial in analyzing real-world scenarios like airbags in cars, which extend the time of impact, reducing the force and protecting passengers.

Forms of Energy:

• Kinetic Energy: Energy due to motion. Example: A moving car.
• Potential Energy: Energy stored due to position. Example: Water in a dam.
• Thermal Energy: Energy due to the temperature of an object. Example: Heat from a stove.
• Chemical Energy: Energy stored in chemical bonds. Example: Batteries, fuel.
• Electrical Energy: Energy from the flow of electric charge. Example: Electricity in a circuit.
• Sound Energy: Energy carried by sound waves. Example: Music from a speaker.
• Light Energy: Energy from visible light. Example: Sunlight.
• Nuclear Energy: Energy from nuclear reactions. Example: Energy from nuclear fission.

Principle of Conservation of Energy:

Principle of conservation of energy states that energy cannot be created or destroyed; it can only be transferred or transformed from one form to another.

Energy Transfers:

Energy transfers occur in various ways. Examples:

• Electrical energy in a heater converts to thermal energy.
• Chemical energy in food transforms into kinetic energy when a person runs.

Electricity Generation:

• Thermal Power Stations: Coal is burned to heat water, producing steam that drives turbines to generate electricity.
• Nuclear Power Stations: Nuclear fission releases energy, heating water to create steam for turbines.
• Geothermal Sources: Heat from volcanic areas or hot rocks generates steam for turbines.
• Solar Energy: Solar panels convert sunlight into electricity; solar cells store energy.
• Wind Energy: Wind turbines convert kinetic energy from wind into electricity.
• Hydropower: Water flowing through dams generates electricity.

Advantages and Disadvantages of Energy Sources:

Energy Source	Advantages	Disadvantages
Solar	Renewable, no emissions	Expensive setup, weather-dependent
Wind	Renewable, no emissions	Intermittent, noise pollution
Coal	Abundant, reliable	Pollution, greenhouse gases
Hydropower	Renewable, reliable	Impact on ecosystems
Nuclear	High energy output	Radioactive waste

Energy Efficiency:

Definition: Energy efficiency is defined as the ratio of useful energy output to total energy input, expressed as a percentage.

Formula: Efficiency = (Useful Energy Output / Total Energy Input) × 100%

Work:

Definition: Work is defined as done when a force moves an object in the direction of the force.

Formula: Work = Force × Distance

Units: Joules (J).

Work done is related to potential energy: PE = mgh, where m is mass, g is gravitational field strength, and h is height.

Kinetic Energy:

Formula: KE = 0.5 × m × v²

Units: Joules (J).

Power:

Definition: Power is defined as the rate of doing work or transferring energy.

Formula: Power = Work Done / Time

Units: Watts (W).

Energy Flow and Diagrams:

Energy flow diagrams and Sankey diagrams visually represent energy transfers and losses.

Example:

• 100 J input energy in a bulb → 20 J light energy (useful) + 80 J heat energy (wasted).

IGCSE Notes Physics on Pressure:

Definition of Pressure:

Pressure is defined as the force applied per unit area on a surface.

Formula and Units:

Formula: Pressure (P) = Force (F) / Area (A)

• Units: Pascals (Pa) or N/m².
• Force is measured in Newtons (N), and area is measured in square meters (m²).

Pressure Word Problem:

Problem: A force of 200 N is applied on a surface area of 2 m². Calculate the pressure.

Solution:

P = F / A = 200 N / 2 m² = 100 Pa

Real-Life Applications of Pressure:

• Hydraulic Systems: Pressure is used to lift heavy loads in hydraulic jacks and cranes.
• Tires: Proper air pressure ensures smooth operation and safety.
• Cutting Tools: Sharp knives concentrate force on a smaller area, increasing pressure for effective cutting.

Advantages and Disadvantages of Pressure:

• Advantages: Effective in hydraulic systems, medical applications (e.g., syringes), and industrial machinery.
• Disadvantages: High pressure can lead to equipment failure or danger if not managed properly.

Pressure Exerted by Fluids:

Fluids exert pressure in all directions. The pressure increases with depth due to the weight of the fluid above.

Formula: P = h × ρ × g

• h: Height of the fluid column (m)
• ρ: Density of the fluid (kg/m³)
• g: Acceleration due to gravity (9.8 m/s²)

Factors Influencing Solid and Liquid Pressure:

• Solid Pressure: Depends on the force applied and the area over which the force acts.
• Liquid Pressure: Depends on the depth of the liquid, its density, and gravitational force.

Applications of Fluid Pressure:

• Hydraulic Systems: Used in car brakes and lifts.
• Dams: Designed to withstand the pressure of water at different depths.
• Submarines: Built to handle high water pressure at great depths.

Word Problem:

Problem: Calculate the pressure exerted by water at a depth of 10 m. The density of water is 1000 kg/m³.

Solution:

P = h × ρ × g = 10 m × 1000 kg/m³ × 9.8 m/s² = 98,000 Pa