Free Fall With Photocell Gates
To measure the acceleration of gravity.
Photocell gate timer, cylindrical mass with plastic tube mounted as photographed.
The gates are set about x = 50 cm apart along the vertical line defined by the guide tube. A short aluminum cylinder is held immediately above the top photocell beam and released. The acceleration of gravity is then detemined using the equation g = 2 x / t**2. ◙