Chapter 1
Force & Pressure
Pressure Formula
SI: Pascal (Pa) = N/m²Pressure (P) = Force (F) / Area (A)
Pressure is inversely proportional to contact area. A smaller area exerts greater pressure for the same force.
Variables: F = Normal force (N), A = Contact surface area (m²)
Exam Tip: Why nails have sharp tips and heavy school bags have broad straps: sharp tip reduces area to maximize pressure; broad strap increases area to reduce shoulder pressure.
Liquid Pressure Relation
SI: Pascal (Pa)P = ρ × g × h
Pressure inside a fluid increases linearly with depth and acts equally in all directions.
Variables: ρ = liquid density (kg/m³), g = acceleration due to gravity, h = liquid depth (m)
Exam Tip: Dams have thicker walls at the bottom because water pressure increases with depth.
Chapter 2
Sound & Acoustics
Frequency & Time Period
SI: Hertz (Hz)Frequency (f) = 1 / Time Period (T) | f = Number of Oscillations / Time (s)
Frequency determines the pitch (shrillness) of sound; Amplitude determines the loudness.
Variables: f in Hertz (Hz), T in seconds (s)
Exam Tip: Audible human hearing frequency range is 20 Hz to 20,000 Hz. Below 20 Hz is infrasonic, above 20 kHz is ultrasonic.