4. George walks to a friend’s house. He walks 750 meters South, then realizes he walked too far. He turns around and walks 250 meters North. The entire walk takes him 12 seconds. What is his velocity per second?

5. A roller coaster is moving at 25 m/s at the bottom of a hill. Three seconds later it reaches the top of the hill moving at 10 m/s. What was the acceleration of the coaster?
6. A car traveling at 30 m/s starts to decelerate steadily. It comes to a complete stop in 10 seconds. Find the cars acceleration.