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Measuring and the pendulum

How can you time one swing of a pendulum accurately?

Read a rule and a measuring cylinder without parallax or zero errors, then time a pendulum with your own finger on the stop-clock: one swing, then twenty, then other lengths, and plot period against length.

A playground swing caught mid-swing, with faint earlier positions showing its arc.

Choose a module in the contents to start reading, or open a part below.

In this module

  1. Read the scale

    Reading rulers and measuring cylinders, and measuring small distances by multiples

  2. Time the swing

    Timing with clocks and timers, and the period of a pendulum from many swings

Syllabus statements for this topic · for teachers · 74 statements

Core for every pupil · Supplement also for Extended entry. Paraphrased from the Cambridge IGCSE Physics 0625 syllabus (2026–2028); check the official syllabus for exact wording.

1.1 Physical quantities and measurement techniques

Covered in Measuring and the pendulum, Resultant force

  • 1.1.1Rulers and measuring cylinders for length and volumeC
  • 1.1.2Timing intervals with clocks and digital timersC
  • 1.1.3Averaging small distances and short times from multiplesC
  • 1.1.4Scalars have size; vectors have size and directionS
  • 1.1.5Which quantities are scalarsS
  • 1.1.6Which quantities are vectorsS
  • 1.1.7Resultant of two perpendicular forces or velocitiesS

1.2 Motion

Covered in Speed and motion graphs, Acceleration, falling and drag

  • 1.2.1Speed as distance per time; v = s/tC
  • 1.2.2Velocity is speed in a stated directionC
  • 1.2.3Average speed from total distance and total timeC
  • 1.2.4Drawing and reading distance–time and speed–time graphsC
  • 1.2.5Rest, steady speed, speeding up, slowing from graphsC
  • 1.2.6Speed from a distance–time gradientC
  • 1.2.7Distance from the area under a speed–time graphC
  • 1.2.8Free-fall acceleration g ≈ 9.8 m/s² near EarthC
  • 1.2.9Acceleration as velocity change per time; a = Δv/ΔtS
  • 1.2.10Constant versus changing acceleration on speed–time graphsS
  • 1.2.11Acceleration from a speed–time gradientS
  • 1.2.12Deceleration as negative acceleration in calculationsS
  • 1.2.13Falling with and without drag; terminal velocityS

1.3 Mass and weight

Covered in Mass, weight and density

  • 1.3.1Mass as the quantity of matterC
  • 1.3.2Weight as the gravitational force on a massC
  • 1.3.3g = W/m; field strength equals free-fall accelerationC
  • 1.3.4Comparing weights and masses on a balanceC
  • 1.3.5Weight as a gravitational field acting on massS

1.4 Density

Covered in Mass, weight and density

  • 1.4.1Density as mass per volume; ρ = m/VC
  • 1.4.2Measuring density of liquids, regular and irregular solidsC
  • 1.4.3Predicting floating from density dataC
  • 1.4.4Predicting which immiscible liquid floats on anotherS

1.5.1 Effects of forces

Covered in Acceleration, falling and drag, Resultant force, Stretching springs

  • 1.5.1.1Forces can change size and shapeC
  • 1.5.1.2Load–extension graphs and the spring experimentC
  • 1.5.1.3Resultant of forces along one lineC
  • 1.5.1.4No resultant force: rest or steady straight motionC
  • 1.5.1.5A resultant force changes speed or directionC
  • 1.5.1.6Solid friction opposes motion and heats surfacesC
  • 1.5.1.7Drag on objects moving through liquidsC
  • 1.5.1.8Drag in gases: air resistanceC
  • 1.5.1.9Spring constant as force per extension; k = F/xS
  • 1.5.1.10Limit of proportionality on a load–extension graphS
  • 1.5.1.11F = ma; force and acceleration share directionS
  • 1.5.1.12Circular motion: force, speed, radius and massS

1.5.2 Turning effect of forces

Covered in Moments and balance

  • 1.5.2.1Moment as turning effect; everyday examplesC
  • 1.5.2.2Moment = force × perpendicular distance from pivotC
  • 1.5.2.3Principle of moments with one force each sideC
  • 1.5.2.4Equilibrium: no resultant force and no resultant momentC
  • 1.5.2.5Principle of moments with several forces each sideS
  • 1.5.2.6Experiment showing no resultant moment in equilibriumS

1.5.3 Centre of gravity

Covered in Moments and balance

  • 1.5.3.1Meaning of centre of gravityC
  • 1.5.3.2Finding the centre of gravity of a laminaC
  • 1.5.3.3Centre of gravity position and stabilityC

1.6 Momentum

Covered in Momentum and collisions

  • 1.6.1Momentum p = mvS
  • 1.6.2Impulse = FΔt = Δ(mv)S
  • 1.6.3Conservation of momentum in one dimensionS
  • 1.6.4Resultant force as rate of change of momentumS

1.7.1 Energy

Covered in Energy, work and power

  • 1.7.1.1Energy stores: kinetic, gravitational, chemical, elastic and othersC
  • 1.7.1.2Transfers between stores by forces, currents, heating, wavesC
  • 1.7.1.3Conservation of energy with simple flow diagramsC
  • 1.7.1.4Kinetic energy Ek = ½mv²S
  • 1.7.1.5Change in gravitational potential energy ΔEp = mgΔhS
  • 1.7.1.6Multi-stage energy conservation and Sankey diagramsS

1.7.2 Work

Covered in Energy, work and power

  • 1.7.2.1Work done equals energy transferredC
  • 1.7.2.2Mechanical work W = Fd = ΔEC

1.7.3 Energy resources

Covered in Energy resources

  • 1.7.3.1How each energy resource gives useful energy or electricityC
  • 1.7.3.2Comparing resources: renewability, reliability, scale, impactC
  • 1.7.3.3Efficiency of energy transfer, qualitativelyC
  • 1.7.3.4The Sun behind most energy resourcesS
  • 1.7.3.5Nuclear fusion releases the Sun's energyS
  • 1.7.3.6Research into fusion power stationsS
  • 1.7.3.7Efficiency from energy or power, as a percentageS

1.7.4 Power

Covered in Energy, work and power

  • 1.7.4.1Power as work or energy per unit timeC

1.8 Pressure

Covered in Pressure

  • 1.8.1Pressure as force per area; p = F/AC
  • 1.8.2Pressure, force and area in everyday examplesC
  • 1.8.3Liquid pressure rises with depth and densityC
  • 1.8.4Liquid pressure change Δp = ρgΔhS

Cambridge IGCSE 0625 · 26 of 43 modules ready