This past summer my family and I went to Six Flags in New Jersey. My dad and I rode the Kingda Ka which supposedly is the fastest, tallest roller coaster in the world. While we were waiting in line, there were signs that told us that in the first 3.5 seconds of the ride, we'd accelerate from 0 mph to 128mph. I calculated this to an acceleration of 16.35 m/s squared. The tallest point of this roller coaster is 456 feet and the whole ride lasted less than a minute. I experienced positive acceleration first, then negative acceleration when we were shot vertically into the air (because we slowed down while going in a positive direction) and then negative acceleration again when dropped straight down (speeding up while going in the negative direction). This ride was craziest thing ever and I was speechless/couldn't move afterwards but I'm glad I decided to ride it.