Question

A mass attached to a spring is pulled towards the floor then let go. Its height is recorded and

Answer 1

First find the derivative,

$\dfrac{d}{dt}\Big(-10\cos(4t)\Big)=40\sin(4t)$.

Then find the critical point,

$40\sin(4t)=0\implies t=40\mathrm{s}$.

Hope this helps.

I am a little rusty here :(.