6-30. A pair of springs and masses vibrate under simple harmonic motion, as shown in Fig. P6.30. The positions of the masses in inches are given by y(t)=52 cos(21+) and y2(f) = 10 cos(21), where I is in seconds. (a) Write down the amplitude, frequency (in hertz), period (in seconds), phase shift (in degrees), and time shift (in seconds) of the position of the first mass y(I). (b) Plot one cycle of the position y(t), and indicate the earliest time after 1=0 when the position is zero. (c) The vertical distance between the two masses is given by 6(t) = y(1) - y2(f). Write (1) in the form 5(r) = Msin(2x1+0); in other words, find M and 0. 184 Chapter 6 Sinusoids in Engineering 3(1) 32(1) Figure P6.30 A pair of springs and masses for problem P6-30.