I came across this question:

> 
> A particle performs simple harmonic with amplitude A. Its speed is trebled at the instant that it is a distance 2A/3 from equilibrium position. The new amplitude of the motion is:
> 
> 
> 

The solution to this question is given in this link:
<https://www.sarthaks.com/195678/a-particle-performs-simple-harmonic-motion-with-amplitude-a>

However, I do not understand why the change in velocity only affects the amplitude, and not the angular frequency. After searching this site for a suitable answer, I found this:

[Why does angular frequency of a particle in SHM does not change when it's velocity is changed](https://physics.stackexchange.com/questions/456849/why-does-angular-frequency-of-a-particle-in-shm-does-not-change-when-its-veloci)

But doesn’t the change in velocity imply there must have been some acceleration, which would have been caused by some additional forces? So why doesn’t the angular frequency change?

Any help would be appreciated.