1. Timing Falling Bodies Time

2. Ships at Sea Latitude – position North/South equals the height of the North Star above the horizon 1/60 degree = one nautical mile Longitude – position East/West The stars rise in the east and set in the west. At the equator you are going 1000 mph To know your longitude you needed to know the exact time.

3. Galileo In 1582, while praying in a church, Galileo observed the chandeliers swinging. He timed the swings against his own heartbeat. The period of the pendulum does not change with the size of the arc of the swing. (approximately)

4. U.S. Naval Observatory Washington, DC Today: Atomic Clocks Vice President’s Residence

5. Electricity Which side is positive? The positive side alternates 60 times each second Positive to negative and back is one cycle The period is 1/60 second Oscillates 60 cycles/sec The Philadelphia Electric Company Provides Electric Energy and Timing Signals