Ticker tape timer is a device which punches dots on a tape at specific time interval. The tape can be attached to a moving object. With information of the frequency of the ticker timer and the spacing of the dots, we are able to analyse the motion of the moving object.
View the following videos to understand more about the ticker tape timer and also some typical questions on ticker tape timer.
Explanation of Ticker Tape Timer
Questions on ticker tape timer
Refer to this post for another example of finding acceleration