Disadvantages of manual stopwatch timing

There is always some delay in people's actions, and there is usually a delay of several milliseconds in stopping the stopwatch manually, so the disadvantage of stopping the stopwatch manually is that it is not allowed.

Stopwatch is a time measuring instrument, which consists of pause button, clockwork handle, minute hand and so on. And use the isochronism of the pendulum to control the rotation of the pointer to time. Stopwatches are mainly mechanical and electronic, and electronic watches can be divided into three-key and four-key categories. Nowadays, most PE teachers use electronic stopwatches, and mechanical stopwatches have become history in many places.