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GCSE Physics Edexcel: Key Concepts and Units

1.1 SI Units for Physical Quantities

SI (International System of Units) is the standard system for measurement used in science. Key SI units for physical quantities include:

  • Length: meter (m)

  • Mass: kilogram (kg)

  • Time: second (s)

  • Electric current: ampere (A)

  • Temperature: kelvin (K)

  • Amount of substance: mole (mol)

  • Luminous intensity: candela (cd)

1.2 Multiples and Sub-Multiples of Units

Understanding prefixes for multiples and sub-multiples is crucial for converting between units:

  • Giga (G): 109

  • Mega (M): 106

  • Kilo (k): 103

  • Centi (c): 10-2

  • Milli (m): 10-3

  • Micro (μ): 10-6

  • Nano (n): 10-9

1.3 Converting Between Units

Conversion between different units is often required, particularly time units:

  • Hours to seconds: 1 hour = 3600 seconds

  • Example: 3 hours = 3×3600=10800 seconds

1.4 Significant Figures and Standard Form

Using significant figures and standard form ensures precision and clarity:

  • Significant Figures: Used to represent the precision of a measurement.

  • Standard Form: Expressing numbers as a product of a number between 1 and 10 and a power of 10.

    • Example: 4500=4.5×103

Summary Notes from Topic 1: Key Concepts in Physics

Measurement and Uncertainty

  • Precision and accuracy in measurements.

  • Understanding of errors and how to minimize them.

Scalars and Vectors

  • Scalars: Quantities with magnitude only (e.g., mass, time).

  • Vectors: Quantities with both magnitude and direction (e.g., velocity, force).

Forces and Motion

  • Newton's Laws of Motion.

  • Equations of motion and their applications.

Energy

  • Different forms of energy and energy transfer.

  • Conservation of energy principle.

Waves

  • Characteristics of waves: amplitude, wavelength, frequency, and speed.

  • Types of waves: transverse and longitudinal.

Practical Applications and Problem Solving

Example Problems:

  1. Unit Conversion:

    • Convert 5 kilometers to meters.

    • Solution: 5 km=5×1000=5000m

  2. Significant Figures:

    • Represent the number 0.00456 in 2 significant figures.

    • Solution: 0.0046

  3. Standard Form:

    • Express the number 0.000789 in standard form.

    • Solution: 7.89×10-4