What is a Pendulum? Is a WEIGHT suspended from a PIVOT so it can swing freely. When displaced it is subject to a restoring force due to gravity which allows it to accelerate back and forth. Kinetic vs. Potential The time for one complete cycle, a left swing and a right swing is called the PERIOD.

Building a Pendulum 1. A String or Rod 2. A Weight. 3. Amplitude 4. Gravity

Assumptions Massless rod Massive bob Frictionless pivot Low theta

Pendulums in Technology Pendulum Clocks -Discovery (Galileo Galilei ) -Pendulum Clock (Christiaan Huygens – 1656) - Error - 15 min per day reduced to 15 sec - Replaced by quartz clock in 1930s ***WHY WAS IT USED FOR TIME KEEPING?

Considering the Following.....

Formula for Simple Pendulum T= Period m/s π= 3.14 L= length m g= acceleration due to gravity (9.8m/s²)

Example for Finding Period Ex: Find the period of a pendulum with a string length of 3 meters. Answer = 3.5 seconds

Making the calculations In your groups you will be asked to find the string length for your given periods. Group 1 T= 1 sec Group 2 T = 1.5 sec Group 3 T = 2 sec Answers: G1 =.25m, G2 =.56m, G3 = 1m