According to the principal of wave refraction, when light from the atmosphere enters a medium of greater density at an oblique angle its a. velocity speeds up but angle remains the same b. velocity remains the same but angle changes c. velocity slows down but angle remains the same d. velocity slows down and angle changes

Ablue car pulls away from a red stop-light just after it has turned green with a constant acceleration of 0.5 m/s 2 . a green car arrives at the position of the stop-light 6.5 s after the light had turned green. if t = 0 when the light turns green, at what time does the green car catch the blue car if the green car maintains the slowest constant speed necessary to catch up to the blue car? answer in units of s.