Physics Exam Formulas and Key Concepts

Importance of Formulas

• Physics is math-based with many calculations.
• Knowing formulas is essential for solving questions.

Chapter 1: Motion

• Speed (Velocity): $v = \frac{d}{t}$
  • Distance in meters; time in seconds; velocity in m/s.
• Acceleration: $a = \frac{\Delta v}{t}$
  • Change in velocity over time; measured in m/s².
• Graphs:
  • Distance-time graph gives speed.
  • Speed-time graph gives acceleration (gradient) and distance (area under graph).

Mass and Weight

• Mass: Quantity of matter.
• Weight: $W = m \times g$
  • Mass in kilograms; gravity on Earth is 9.8 m/s²; weight in Newtons.

Density

• Density: $\rho = \frac{m}{V}$
  • Mass in kg; volume in m³; density in kg/m³.
• Related to specific heat capacity questions.

Forces

• Hook's Law: $F = k \times x$
  • Force in Newtons; extension in meters or centimeters; $k$ is spring constant.
• Newton's Laws:
  • Second Law: $F = m \times a$

Moments

• Moment calculation: $\text{Moment} = \text{Force} \times \text{Distance}$
  • Distance must be perpendicular to the pivot.
  • Equilibrium: anticlockwise moment = clockwise moment.

Momentum

• Momentum: $p = m \times v$
  • Mass in kg; velocity in m/s; momentum in kg m/s.
• Impulse: Change in momentum; $\text{Impulse} = \text{Force} \times \text{Time}$

Work, Energy, and Power

• Power: $P = \frac{\text{Work Done}}{\text{Time}}$
  • Power in Watts; work done in Joules.
• Kinetic Energy: $KE = \frac{1}{2} mv^2$
• Potential Energy: $PE = mgh$

Efficiency

• Efficiency = $\frac{\text{Output}}{\text{Input}} \times 100%$

Pressure

• Pressure: $P = \frac{F}{A}$
  • Force in Newtons; area in m²; pressure in Pa or N/m².

Chapter 2: Thermodynamics

• Absolute Zero: $-273°C$
• Boyle’s Law: $P_1V_1 = P_2V_2$
• Specific Heat Capacity: $Q = mc\Delta \theta$

Chapter 3: Waves

• Frequency: $f = \frac{1}{T}$
  • Frequency in Hz.
• Wave Speed: $v = f \cdot \lambda$
  • Wavelength in meters.

Light and Sound

• Refractive Index: $n = \frac{\text{Speed in Air}}{\text{Speed in Medium}}$
  • $n = \frac{\sin \theta_1}{\sin \theta_2}$ (Snell's Law)
• Echoes: Similar formula as speed; adjust for travel and return path.

Chapter 4: Electricity

• Current: $I = \frac{Q}{t}$
  • Charge in Coulombs; time in seconds.
• EMF and Potential Difference
  • EMF: Voltage across battery.
  • Potential difference: Voltage across component.
• Resistance
  • Ohm's Law: $R = \frac{V}{I}$

Electrical Power and Energy

• Power: $P = IV$
  • Energy Transfer: $E = IVt$
• Potential Dividers: Use ratio of resistances to split voltage.

Transformers and Power Losses

• Transformer calculations involve primary/secondary voltage and coil turns.
• Power loss: $P = I^2 R$

Chapter 5: Nuclear Physics

• Nuclear Notation: Identify elements by proton numbers and decay paths.
• Half-life Calculations: Determine decay time and count rates.

Chapter 6: Astrophysics

• Orbital Speed: $v = \frac{2\pi r}{T}$
• Speed of Light: $3 \times 10^8$ m/s
• Hubble's Law: Relates recession velocity to distance.

Ensure to understand and practice problems with these formulas for effective exam preparation. Good luck on your exams!