Answer
$s(1.466)\approx2$
This means that after $t=1.466$ seconds, the weight is about 2 inches above the equilibrium position.
Work Step by Step
We calculate $s(1.466)$ by substituting $t=1.466$ into the equation and solving:
$s(t)=-4\cos 10t$
$s(1.466)=-4\cos (10\times1.466)$
$s(1.466)=-4\cos (14.66)$
$s(1.466)=-4(-0.5)$
$s(1.466)=2$
We know that the motion starts from $-4$ inches. Since the value of $s$ is positive, this means that the weight is moving upwards and has passed the equilibrium position. Therefore, after $t=1.466$ seconds, the weight is about 2 inches above the equilibrium position.
