The CoasterCalc will calculate the maximum and average speed and G-force for a roller coaster ride. Just press the "Start" button and gently place the phone into your pocket. DO NOT put the screen to sleep! After the ride has come to an end, press the "Stop" button as soon as safely possible. The final data will be displayed on the screen. Pressing the start button again will reset the application and start recording data again. Please send email to: [email protected]