In clocks, which of the following is used to measure time?

The simplest device that can be used to measure time based on periodic motion.

Quartz crystal is a crystal of:

1nanosecond =

The device which is used indicate speed in vehicles.

Name the scientist who first proved that the motion of a pendulum is periodic.

Time period of a pendulum depends upon its:

The act or the process of moving is called 

Who invented a pendulum clock for time keeping?

One year =