Time Measurement

1. As in the case of the length, different accuracy is required to calculate the distance between cities and different accuracy to find the thickness of a page, similar situations occur in time measurement. Discuss the accuracy that is required for the measurement of the following times:

2. Set the base up and adjust the device of the pendulum at the top using the boss, as shown in the photo. Use a long metal support rod to create a long pendulum and place a weight at the edge.

• The upper right button “start/stop” stops and initiates the timing.
• When the timer is stopped the upper left button resets the timer.

3. Fill in the table below with the results of the measurements made in step 4 and calculate the average (mean) in each case.

• If differences observed between the values of each column, why do you think that happen? Is the Average affected by the accuracy of measurements?

• Assuming that the analog and digital clocks, that we used, operate properly, the differences must be due to how each student responds in time when switching on and off the timer. The Average measurement differs too, with greater precision closer to the “real” value.
• Nowadays, the development of technology allows the manufacture of timers which have the ability to measure billionths or even trillionths of a second. The operation of these individual timers is based on a simple physical principle, the natural frequency of atoms.

Atoms and molecules emit and absorb electromagnetic radiation at a series of fixed frequencies that depend on their structure. The frequency of the radiation is measured in Hertz. Clocks are mainly composed of two parts: a) the production system of a stable atomic frequency standard, and b) an electronic device to measure the respective oscillations.