In an arcade video game, a spot is programmed to move across the screen according to x = 9.04t - 0.637t³, where x is the distance in centimeters measured from the left edge of the screen and t is time in seconds. When the spot reaches a screen edge, either at x = 0 or x = 16.0 cm, t is reset to 0 and the spot starts moving again according to x(t). 

(a) At what time after starting is the spot instantaneously at rest? 

(b) At what value of x does this occur?

(c) What is the spot's acceleration when this occurs? 

(d) At what time t > 0 does the spot first reach an edge of the screen?