1. Regents Physics
The Simple Pendulum

2. What is a Simple Pendulum?
A simple pendulum consists of a bob or mass attached to a string of negligible mass  l m

3. Where do we find pendulums?
We typically find them in clocks
Very minimal friction
Good for showing conservation of energy

4. The Foucault Pendulum Originally designed to measure
the rotation of the Earth
At either the North Pole or South Pole,
the plane of oscillation of a pendulum remains fixed
with respect to the fixed stars while Earth rotates
underneath it, taking one sidereal day to complete a
rotation.
So relative to Earth, the plane of oscillation of a pendulum at
the North or South Pole undergoes a full clockwise or
counterclockwise rotation during one day, respectively.
When a Foucault pendulum is suspended on the equator,
the plane of oscillation remains fixed relative to Earth.
At other latitudes, the plane of oscillation processes relative
to Earth, but slower than at the pole; the angular speed,
Animation of a Foucault pendulum,
with the rotation rate greatly exaggerated.
The green trace shows the path of the
pendulum bob over the ground, and the
blue trace shows the path in a frame of
reference rotating with the plane of the pendulum.

5. Variables Involved
Period (T) – The time required for the displaced pendulum to complete one cycle of motion – measured in seconds
Frequency (f) – The number of cycles per second – measured in hertz (Hz)
Frequency = 1/T
Both are independent of mass
Amplitude is displaced angle of distance

6. Pendulum Equation T = 2 l g
This equation holds for amplitudes of less than 15 degrees

7. Energy in a Pendulum

8. Pendulum Practice Problem
Calculate the length of a pendulum that posses a 2-second period and is displaced 15° from vertical
2) Choose Equation
1) Write knowns/unknowns
T = 2 s
g = 9.8 m/s2
3) Rearrange and solve
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