In the experiment P1.3.5.3, a ladder with several rungs falls through a forked light barrier, which is connected to the CASSY computer interface device to measure the obscuration times. This measurement is equivalent to a measurement in which a body falls through multiple equidistant light barriers. The height of the falling body corresponds to the rung width. The measurement data are recorded and evaluated using CASSY Lab. The instantaneous velocities are calculated from the obscuration times and the rung width and displayed in a velocity-time diagram v(t). The measurement points can be described by a straight line

whereby v0 is the initial velocity of the ladder when the first rung passes the light barrier.