A mass m$=0\mathrm{.}85$kg hangs at the end of a vertical spring whose top end is fixed to the ceiling. The spring has spring constant k$=140$N$/$m and negligible mass. The mass undergoes simple harmonic motion when placed in vertical motion, with its position given as a function of time by y$($t$)=$Acos$($t$),$ with the positive y$-$axis pointing upward. At time t$=0$ the mass is observed to be at a distance d$=0\mathrm{.}25$m below its equilibrium height with an upward speed of v$0=3$m$/$s$.$

Find the angular frequency of the oscillation, in radians per second.

Calculate the value of A$,$ in meters.

What is the mass's velocity along the y$-$axis, in meters per second, at time t$1=0\mathrm{.}25$s$?$