Acceleration due to gravity from time of fall

    By measuring the time of free fall of a body we can calculate 'g' from the equation S = g * t * t / 2 , where S is the distance and t is the time of flight. Time is done in the following manner.
        An electromagnet is powered to hold a small iron ball. Software then releases the ball and marks the time of start. The ball drops on a flat surface where a loudspeaker is kept face down. The speaker output is amplified and given to the LSB of digital input. When the ball hits the surface the vibrations make the digital input high momentarily. This time interval between releasing the ball and it hitting the plate below is measured by using the program gtfall.py.



The value of 'g' is found by fitting the above curve using a polynomial and the value of g obtained is 979.6 cm/sec2

Details in chapter 1 of this document.