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During oscillatory motion, the acceleration is not constant. The general kinematics relationships are nevertheless valid (remember back from week 2 the following image).

The constant acceleration kinematics equations s-v-v^2 DO NOT hold if the acceleration is not constant.

Oscillating motion

Oscillatory motion is the primary example that we will study in this class of a non-constant acceleration motion.

We will limit our analysis to simple harmonic motion where the motion is sinusoidal.

Check your Understanding.

The first question below is particularly important since this is a common misunderstanding regarding the definition of a "full cycle".

Rad for radian is not a real unit and it is sometimes omitted. It is there to remind us that when you multiply the angular frequency by a time, you get an angle and that angle is in radians, not degrees. Be careful to use rad on your calculator when relevant in your calculations.

The Period Does Not Depend on the Amplitude.

One of the most important properties of harmonic oscillator is that the amplitude and the period (or frequency) are independent. You can change the amplitude as much as you want and the period stays the same.

We illustrates this fact in the following video using a pendulum.

This is why pendulum are often used to keep track of time. Even though the amplitude of the oscillations decreases, the period stays the same and the pendulum keeps track of time!
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