Counterintuitive behaviour of a particle under the action of an oscillating force

摘要

When a free particle initially at rest is acted on by an oscillating force, it is intuitively expected to oscillate in place with the frequency of the force. However, careful solution of the classical equation of motion shows that this is only true for particular initial phases of the force; otherwise a steady drift is superimposed on the oscillation. This counterintuitive outcome, like others, can be used in teaching to help students understand the need to challenge preconceived ideas.