The acceleration of gravity can be measured by projecting a body upward and measuring the time that it takes to pass two given points in both directions.
Show that if the time the body takes to pass a horizontal line in both directions is , and the time to go by a second line in both directions is , then, assuming that the acceleration is constant, its magnitude is where is the height of line above line .
So this is a constant acceleration problem. Also the path is parabolic. How would I deduce the above equality?