Is the car stopwatch accurate? The stopwatch shows 60 yards and the actual speed is 53.2 yards.

With the help of a number of engineers from the Transportation Institute of the Zhejiang Institute of Metrology, the test car was equipped with a non-contact speedometer, which can sense a distance of 1 micron.

The car drove on the Desheng Expressway and tested speeds of 50 kilometers, 60 kilometers, and 80 kilometers per hour in the cruise mode. The non-contact speedometer showed that the actual speed was 44.8 yards, 53.2 yards, and 72.9 yards.

From the experimental results, two points are worth paying attention to: one is that the three tests have a large speed error, the maximum error is 7.1 yards, and the other is that the apparent speed is greater than the actual speed.