Physics

Physics

Problem

A particle moves in simple harmonic motion with amplitude 4.0 cm4.0\,\text{cm} and angular frequency 10 rad s−110\,\text{rad s}^{-1}. At t=0t=0, its displacement is 2.0 cm2.0\,\text{cm} and it is moving in the positive xx-direction. Determine its velocity at t=0.20 st=0.20\,\text{s}.
Intuitive explanation

Simple harmonic motion is governed by a sinusoidal position function, and the key is finding the correct phase constant that matches your initial conditions. Once you know the full equation x(t)=Asin⁡(ωt+ϕ)x(t) = A\sin(\omega t + \phi), taking its derivative gives you velocity at any time. Use the displacement and direction information at t=0t=0 to pin down ϕ\phi, then evaluate the velocity formula at the given time.

Intuitive explanation

Simple harmonic motion is governed by a sinusoidal position function, and the key is finding the correct phase constant that matches your initial conditions. Once you know the full equation x(t)=Asin⁡(ωt+ϕ)x(t) = A\sin(\omega t + \phi), taking its derivative gives you velocity at any time. Use the displacement and direction information at t=0t=0 to pin down ϕ\phi, then evaluate the velocity formula at the given time.

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