Mass on a Spring: a 12

Essay

Mass on a spring: A 12.0-N object is oscillating in simple harmonic motion at the end of an ideal vertical spring. Its vertical position y as a function of time t is given by y(t) = 4.50 cm cos[(19.5 s^-1)t - π/8].
(a) What is the spring constant of the spring?
(b) What is the maximum acceleration of the object?
(c) What is the maximum speed that the object reaches?
(d) How long does it take the object to go from its highest point to its lowest point?