The displacement vs. time for a small mass at the end of a spring is shown. At t=0, x=0.43 cm. (a) If m = 14.3g, find the spring constant k. (b) Write the equation for the displacement x as a function of time (use a cosine function) using numerical values for A, ω and ø. (c) What is the speed of the mass at t = 1.8 s