Notes – Crack A Level

Physics Notes

1) Physical Quantities and Units

• Physical Quantities: Values used to describe phenomena in physics.

• Units: Standard measures for physical quantities.

Base Quantities

• 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)

Derived Quantities

• Force (F): N (Newton) = kg∙m/s²

  • Equation: F = ma

• Pressure (p): Pa (Pascal) = kg/m∙s²

  • Equation: p = F/A

• Energy (E): J (Joule) = kg∙m²/s²

  • Equation: E = F∙d

• Power (P): W (Watt) = kg∙m²/s³

  • Equation: P = E/t

• Charge (Q): C (Coulomb) = A∙s

• Voltage (V): V = W/Q

• Frequency (f): Hz (Hertz) = 1/s

2) Measurement Techniques, Errors, and Uncertainties

• Calibration: Comparing an instrument to a known standard.

• Precision: Closeness of multiple measurements.

• Uncertainty: Natural variations in measurements.

Types of Errors

• Systematic Error: Consistent error in the same direction.

• Random Error: Unpredictable variations.

Calculating Uncertainty

• Maximum uncertainty = max value - mean value

• Percentage uncertainty = (uncertainty / measured value) × 100

3) Kinematics

• Variables:

  • a = acceleration

  • v = final velocity

  • u = initial velocity

  • t = time

  • S = displacement

SUVAT Equations

1. S = ut + 1/2 at²

2. v² = u² + 2aS

3. a = (v-u)/t

4) Dynamics

• Newton's Laws of Motion:

  • 1st Law: An object at rest stays at rest, and an object in motion continues in motion unless acted upon by an external force.

  • 2nd Law: F_net = ma.

  • 3rd Law: For every action, there is an equal and opposite reaction.

• Momentum (p): p = mv

5) Forces, Density, and Pressure

• Density (ρ): ρ = m/V

• Pressure (P): P = F/A

• Moments: Moment = Force × Perpendicular distance

• Principle of Moments: Sum of clockwise moments = Sum of anticlockwise moments.

6) Work, Energy, and Power

• Work Done (W): W = F × d × cos(θ)

• Power (P): P = W/t

• Conservation of Energy: Energy cannot be created or destroyed, only converted.

7) Waves

• Wave Types:

  • Transverse: Particle motion is perpendicular to wave direction.

  • Longitudinal: Particle motion is parallel to wave direction.

• Wave Characteristics:

  • Amplitude: Maximum displacement.

  • Wavelength: Distance between successive points in phase.

  • Frequency: Number of oscillations per unit time.

  • Wave Speed: v = fλ

8) Electric Fields

• Electric Field Strength (E): E = F/q

• Electric Potential Energy (E.P.E): E.P.E = Voltage × Charge

9) Electric Current and DC Circuits

• Current (I): Rate of flow of electric charge, I = Q/t

• Ohm's Law: V = IR

  • V = Voltage, I = Current, R = Resistance

• Power (P): P = IV

10) Summary of Important Equations

• Force: F = ma

• Pressure: P = F/A

• Work: W = Fd cos(θ)

• Power: P = W/t

• Momentum: p = mv

• Kinetic Energy: KE = 1/2 mv²

• Potential Energy: PE = mgh

• Density: ρ = m/V

Additional Notes

• Understanding scalars (magnitude only) and vectors (magnitude and direction) is crucial in physics.

• Measurements should always account for significant figures to reflect precision.