I NEED HELP ON C THROUGH F. THANK YOU

A spring id vertically, as shown below, and a 500g mass is hung from its lower end. The EQUILIBRIUM extension of the spring is observed to be 10.0cm.
(1) What is the spring constant of the spring?
ANSWER: 49N/m

(B) If the is pulled down by 5.00cm and released, what is the frequency of the subsequent oscillations. ANSWER: 1.58

(C) What ist he velocity of the mass at time t=2.5 sec?

(D) What is the acceleration of the mass at time t=4.75 sec?

(E) What is the net force acting on the mass at time t=5.0sec?

(F) What are the potential and kinetic energies of the mass when the displacement 7 =-1.5cm?

from a)and b) (I didn't check them)

y=5cos(wt) where w=2PIF

so
velocity=-5w sin(wt) solve for velocity in c,

acceleration=-5w^2 coswt solve for acceleration in d

Force= mass*acceleration in e

PE= 1/2 k x^2
KE= 1/2 m v^2