Oscillations is a core part of A-Level Physics. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Simple harmonic motionAcceleration is proportional to displacement and directed to the centre.
Restoring forceA force always directed back to the equilibrium position.
Amplitude & periodMaximum displacement and the time for one oscillation.
Angular frequencyω = 2πf, linking frequency to the motion.
DampingLoss of energy reducing the amplitude over time.
ResonanceLarge amplitude when driven at the natural frequency.
Free oscillationAt natural frequency, no damping.
Light dampingSlow exponential amplitude decay.
Critical dampingFastest return without overshoot.
ForcedExternal periodic driver applied.
Hooke's lawF = −k x; restores towards equilibrium.
Mass-spring TT = 2π √(m/k).
Pendulum TT = 2π √(L/g) for small swings.
Small angle limitsin θ ≈ θ; needed for pendulum SHM.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
In simple harmonic motion, where is acceleration greatest?✗ It stays constant throughout the motion. ✓ At maximum displacement; it is zero at the equilibrium position.
Does a simple pendulum's period depend on the mass of the bob?✗ Yes, a heavier bob gives a longer period. ✓ No — for small swings it depends on length and g, not mass.
Where is the restoring force largest in SHM?✗ At the centre of the motion. ✓ At maximum displacement; it is zero at equilibrium.
If an object is moving at constant velocity in a straight line, what is the net force on it?✗ There must be a forward force on the object to keep it moving. ✓ Zero — by Newton's first law, constant velocity requires zero net force.
For a projectile launched horizontally, what affects the horizontal component of velocity during flight (ignoring air resistance)?✗ Gravity slows down both the vertical and horizontal motion. ✓ Nothing — horizontal velocity stays constant; only vertical velocity changes due to gravity.
Practise Oscillations — free games
Test yourself with these quick revision games for this topic:
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