Balloon Collisions in High Speed

Cayla Noble, Heather Faircloth, Dylan Selinger

The North Carolina School of Science and Math

We built a contact trigger and flash setup using two metal plates, wires, and a flash unit. Then we placed the flash unit on a table top, under a trap door contraption that would drop two balloons at the same time. One balloon fell to hit the table, and the other balloon hit the flash trigger. For purposes of explanation, we will call the balloon dropped on the raised pad balloon 1, and the balloon dropped on the trigger balloon 2.We then slowly raised the height of balloon 1 by adding mouse pads of about 1/4 inch one at a time, while leaving the height of the trigger constant. This allowed for us to capture the impact of balloon 1at various different times. As we decreased the distance between balloon 1 and where it impacted, it had more time to compress before balloon 2 triggered the flash. Using this method we could effectively vary the amount of compression of the balloon.
These pictures are in sequence from just before collision to when it was beginning to bounce back up into the air. We achieved this by raising the landing area for the subject between shots. The last few photos are of our set up and contact trigger.


Here we had the trigger slightly raised so that we could catch the balloon before the collision.	In this photo the balloon was caught just as it touched the target. The balloons were both level at this point.	Here we began to add mouse pads under the subject, catching it during collision. This is with one mouse pad.	Two mouse pads have been added; notice the beginning of the ripples in the top of the balloon.

After the third mouse pad; the subject balloon beginning to flatten out.	After four mouse pads; at this point in the project we were experimenting with the f-stop, contributing to the blurriness.	Five mouse pads, and the balloon is beginning to reach the middle stage of collision.	After adding the sixth mouse pad, the subject had completely flattened and showed rippling.

In this photo, the subject balloon was showing signs of beginning to bounce back up. This was after the seventh mouse pad was added.	In this photo, the balloon is still raising back up in the middle, where all the water is collected. Eight mouse pads were used here.	Notice the point in the middle of this balloon; the water is beginning to slush upward. This is after nine mouse pads.	Here the balloon is still flat and rising. This is after ten mouse pads.


Here the balloon is still obviously beginning to bounce back upwards. This is after eleven mouse pads have been placed beneath the landing area.	Here the balloon is still coming back up on a stage of twelve mouse pads. Notice the beginning of the center point.	Notice how much higher the green balloon is over the orange one setting off the trigger; this is after thirteen mouse pads.	Look at the point in the center of the balloon from the water pushing back upwards. Pictured with fourteen mouse pads.

Notice the ripples and lines around the edge of this extremely flattened balloon; this is after fifteen mouse pads have been placed beneath.	Obviously in the latest stage of rising, the outside is retaking its shape. Pictured after sixteen mouse pads.	Our last photo of the collision; showing the balloon right as it's bouncing back up from its flattened position. It took seventeen mouse pads to achieve this effect.