Physics

Problem

At a fixed point on a stretched string, the displacement becomes zero at

t = 0\,\text{s},\;0.02\,\text{s},\;0.04\,\text{s}

and so on. The first maximum positive displacement of

+3\,\text{cm}

occurs at

t = 0.01\,\text{s}

. (i) Find the time period of the wave at this point. (ii) Calculate its frequency. (iii) State the amplitude of the wave.

Intuitive explanation

This problem is about reading the periodic motion of a single point on a vibrating string—not tracking the wave across space, but watching one spot oscillate up and down. The key insight is that the times when displacement equals zero tell you how the oscillation is divided: the string passes through zero, reaches a peak, returns through zero, hits a trough, and comes back to zero again. Use the zero-crossing pattern and the location of the first maximum to reconstruct the full period, then frequency and amplitude follow directly.

Intuitive explanation

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