Motion, forces and energy

1.1 Physical quantities and measurement techniques

Covered in Measuring and the pendulum

• 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

• 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

• 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

• 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

• 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

• 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

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

1.7.3 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

• 1.7.4.1Power as work or energy per unit timeC

1.8 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