Suppose astronomers discover a radio message from a civilization whose planet orbits a star 35 light-years away. Their message encourages us to send a radio answer, which we decide to do. Suppose our governing bodies take 2 years to decide whether and how to answer. When our answer arrives there, their governing bodies also take two of our years to frame an answer to us. How long after we get their first message can we hope to get their reply to ours? Enter your answer in years.

While strolling downtown on a saturday afternoon, you stumble across an old car show. as you are walking along an alley toward a main street, you glimpse a particularly stylish alpha romeo pass by. tall buildings on either side of the alley obscure your view, so you see the car only as it passes between the buildings. thinking back to your physics class, you realize that you can calculate the car's acceleration. you estimate the width of the alleyway between the two buildings to be 6 m. the car was in view for 0.6 s. you also heard the engine rev when the car started from a red light, so you know the alpha romeo started from rest 4 s before you first saw it. find the magnitude of its acceleration.