lo2 feb 1 (mychelle wong l2 m - orange)

The Reasons Why Swinger Girl Never

Made it Over the BarExplained using the concepts of Damped

Oscillation!

Some of you may be familiar with the Disney cartoon...

RECESS!!

http://o.canada.com/technology/gaming/disney-infinity-5-disney-characters-that-are-a-perfect-fit-for-the-game

In the show there is this character named, Swinger Girl. For those who aren’t familiar with the show, Swinger Girl’s mission is to swing over the swing set bar and loop around... http://vignette4.wikia.nocookie.net/recess/images/4/47/216462_1239072689503_full.jpg/

revision/latest?cb=20110422213830

However, she never did throughout this show (which aired for 4+ years!)...

So how can we explain those 4+ years of failures? If we apply physics to this we can figure out why!

First off...● We need to see

that: o A swing is

basically a simple pendulum whose motion is periodic and has simple harmonic motion

If this were a simple pendulum, all she would have had to do is start at a height close to 180° above the swing set and she would have succeeded as a perfect pendulum oscillates indefinitely.

However!There is more than just that! We need to take into account the forces that are one the swing!

http://www.gettyimages.ca/detail/photo/swing-royalty-free-image/119090965?Language=en-GB

Tension Force

Applied Forces: ● Inertia force ● Forces due to kinetic

energyOpposing forces:

● Tension● Friction:

o between object and the chain

o between the individual chain links when the swing moves

o between the chain and the rigid support

● Drag Force: forces that an object experiences when moving through a medium (eg. air) with a velocity

Tension Force

One reason for her failure was that there were too many forces acting against her...

Tension Force

Simple harmonic motion is modified by dampening forces and results in:● The exponential decrease in the

amplitude of the oscillator over time ● An oscillation frequency of a

undamped oscillator larger than the oscillation frequency of a damped frequency

In turn, the simple harmonic oscillator loses energy (provided by Swinger Girl).

1. As the system loses amplitude, so does it energy, Esimple

harmonic motion= Amplitude2. To move against the drag force, work is done by the

system and uses energy.3. The dampened oscillator takes more time to complete

a cycle because it slows down

Moving against the drag force is like being splashed in the face by air from the front and the back with your whole body (but in a less dramatic way of course!). Since energy is used in forms like this, the swing doesn’t move like a simple harmonic oscillator.

http://media.giphy.com/media/tlijLlismllTy/giphy.gif

This makes this an underdamped oscillation, meaning that the amplitude decreases exponentially with time due to the drag force.

As the system continues to oscillate, a fraction of the energy will be converted to other types of work with each oscillation. This will continue until the system loses all of its energy and stops.

Now that we know the effects of undamped oscillation, other frictional forces and taking into account the total energy that a little elementary school girl has and how fast she can “pump” all that energy into pushing herself over a swing set in 15 minutes. Its basically impossible for her to swing over the swing set all by herself (based on damped oscillation, there are other factors too).

However!

I won’t say that this is an impossible feat. It is still possible, (https://www.youtube.com/watch?

v=OZ9GuJybU0E). If she had an external force pushing her and different equipment it could be possible, but that’s a different chapter for a different time!

Thanks! I hope this helped! :)