Program 27: Parachutes Redux

parachute_forcesI felt it was about time for our G3 scientists to revisit one of our earliest programs, so in October both of our classes tackled parachutes and the forces that maneuver them. I started our programs with a short discussion about what a force is. For example, a push force could be something like one person pushing another person backwards. An example of a pull force could be gravity itself, and how gravity pulls objects downward toward the earth’s surface. Forces have the ability to change the speed or even the direction of an object. We also talked about the forces at work when someone is using a parachute. When somebody jumps out of a plane and parachutes to the ground, two key push and pull forces are in action. Gravity rapidly pulls the person toward the ground. Then the parachute helps to provide a crucial push force that slows a person’s descent and keeps them from smacking into the ground. How is this push force created? Air collects under the parachute and provides resistance, or drag, that essentially pushes back against the “pull” of gravity and makes a person fall at a much slower and safer rate to the ground.

A year ago, I had shared a video with our group showing Joseph Kittinger’s world record free-fall parachute jump from an unprecendented height. In 1960, not only did he become the first man in space, but as of last year he held the world record for the longest free-fall parachute jump! Wearing a special pressurized suit, he rapidly climbed skyward in a helium balloon – so high that he broke through the troposphere and could look back on the earth from the darkness of space. And then, he did the unthinkable – he jumped!  However, as of 2012, Felix Baumgartner (using similar methods to Kittinger) became the new world record holder, finally breaking Kittinger’s longstanding record. In fact, he broke three world records! He now holds world records for…

  1. The highest manned balloon flight (at over 128,000 feet)
  2. The highest freefall distance (of about 120,000 feet)
  3. The record for being the first free-falling human to break the sound barrier (his top speed was around 833 miles/hour, and the speed of sound is around 761 miles/hour).

Kittinger actually still holds the world record for the longest freefall duration at 5 minutes and 35 seconds (Baumgartner did a free-fall for 4 minutes and 20 seconds). Though it should be no surprise that Baumgartner was unable to break this record since he also fell at a quicker rate than Kittinger. Below is a highlight video of Baumgartner’s jump.

OUR EXPERIMENT

To test both push and pull forces, the task of the day for our G3 scientists was to create and release their very own parachutes! An example of a simple parachute design can be found on the website for PBS’s program FETCH (though there are many similar experiment instructions to be found online). Our materials for the parachutes were simple enough:

  • 10″ x 10″ squares cut from plastic garbage bags
  • 10″ x 10″ squares cut from tissue paper
  • 9″ x 9″ squares cut from cloth
  • paperclips (our “human beings”)
  • String
  • tape

Photo Oct 17, 4 53 39 PMThe real challenge was figuring out which material made for the best parachute (in other words, the slowest drop to the ground). Each G3 scientist was instructed to first do a test launch of a parachute using a single square of each type of material. In this way, they could get a sense for which material might make for the best parachute. Once each of the 3 materials were tested, the scientists were given the freedom to design their own parachutes by combining materials, using additional paperclip weights, etc. Our scientists launched their parachutes by climbing a tall ladder (always under the watchful eye of fellow librarian, Kelley). I timed all launches with my handy stop watch, and all scientists had pieces of paper to record their various times on.

Early in our testing, it became obvious that the cloth squares were too heavy and fell pretty quickly to the ground. However, both the garbage bag squares and the tissue paper squares provided some excellent “hang time” in the air. Our best parachutes from each class (the longest time in the air) were both constructed of multiple garbage squares taped together. In both cases, we had good air time solidly over 4 seconds! Below is a video montage of many of our parachute runs from both class days. I hope everyone had as much fun testing their parachutes as I had watching the test runs!

I’m looking forward to seeing everybody again in November when we pick up with the next session of G3 programs 🙂

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