IB Physics: Mechanics Revision

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Two balls of different mass are dropped in a vacuum — which lands first?

Mechanics is a core part of IB Physics. Revise the key concepts and common mistakes below, then lock them in with the free games.

Key concepts

DisplacementVector position change (m)

Velocityds/dt (m/s, vector)

Accelerationdv/dt (m/s², vector)

SUVATv=u+at, s=ut+½at², v²=u²+2as

v-t graphslope = a, area = s

ProjectileConstant g downward

Newton 1No net force → constant velocity (inertia)

Newton 2F = ma

Newton 3Equal opposite reaction

Momentum pmv (kg m/s, vector)

ImpulseFΔt = Δp

ConservationTotal p unchanged in isolated system

Work WF · d · cosθ (J)

Kinetic energyKE = ½mv²

Learn Mechanics step by step

Free interactive mini-lessons: short screens, worked examples and quick checks. Pick your exam board to open its course map, then tap L on this topic:

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Common mistakes to avoid

Questions where students often pick the tempting wrong answer — make sure you know the right one:

Two balls of different mass are dropped in a vacuum — which lands first?✗ The heavier ball lands first because gravity pulls it harder. ✓ They land together; in a vacuum all objects fall with the same acceleration.

A car moves at a steady speed in a straight line. What is the resultant force?✗ A forward force, because it keeps moving. ✓ Zero — the forces are balanced at constant velocity.

Practise Mechanics — free games

Test yourself with these quick revision games for this topic:

▶ Two Truths, One Lie ▶ Reveal Race ▶ Connections Grid ▶ Falling Words ▶ Word Web

See all 22 games in the Revision Arcade →

More IB Physics topics

← IB Physics Next: Thermal Physics →

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