A mass of 625 grams is attached to the end of a spring that is stretched 360 cm by a force of 25 N. At time t = 0 the mass is pulled 1 meters to the right, stretching the spring, and set in motion with an initial velocity of 3 m/s to the left. a. Enter the spring constant k. k = 125/18 b. Set up a differential equation that describes this system. Let x to denote the displacement, in meters, of the mass from its equilibrium position, and give your answer in terms of x, x', x" Assume that positive displacement means the mass is farther from the wall than when the system is at equilibrium. 3.6x"+(125/18) x=0 c. Find the resulting displacement x(t) of the mass in the form x(t) = A cos(omega t - delta), the amplitude and the period of the motion of the mass. (Give all of your answers in units of kg, m and s, and assume that there is no friction.) x(t) = amplitude = period =