Experiencing Extreme Acceleration You experience accelerations every day of your life. Just lying in bed you feel accelera- tion equal to g, due to Earth’s gravitational pull. When you travel in a car or plane, ride an elevator, and especially when you enjoy amusement park rides, your body is sub- jected to additional accelerations, though rarely exceeding 2 g. But jet pilots and astro- nauts experience accelerations many times that caused by Earth’s gravitational pull during takeoffs, sharp turns, and emergency ejections. What happens to the human body under extreme acceleration, and how can equipment be designed to reduce the risk of injury? In the early days of rocket flights and high-speed jet design, government scientists had to know.