Data logger

The connected timer or data logger starts when the leading edge of the card breaks the beam and stops when its trailing edge clears it. The trolley has travelled one card length during the recorded time, so divide the card length by that time to find its speed as it passes the gate.

A data logger can take frequent readings automatically. A temperature probe records temperature, while a suitable electronic balance or mass sensor records mass. The logger attaches a time to each pair of readings, allowing tables or graphs of temperature and mass against time to be produced.