Let’s say your friend has got you trapped in a Chinese finger trap and you suddenly realize that your shirt is inside out. Is it possible to turn it right side out without having to figure out how to get your fingers untrapped? And if you can, what does this tell us about our world?
Student Guide
Losing Your Shirt
Experimenting with constraints
Is it possible to turn a t-shirt inside out while your hands are tied together?
This resource was originally published in PhysicsQuest 2014: Quantum.
Is it possible to turn a t-shirt inside out while your hands are tied together?
- Chopsticks
- Plastic zip tie
- Playdough
- Small bag
- Adhesive tape
- Scissors
- Pen or marker
Intro
Before the experiment
Think about a t-shirt, or better yet, if someone has an extra gym shirt, take a look at it. How many sides does it have?
Can you turn the shirt inside out? How?
Can you think of other ways to turn it inside out? List them all here.
What might make it hard to turn the shirt inside out?
Setting up
Separate the chopsticks and pick one to be your “stick person.” If you want, use the marker to draw a face on the stick person.
Take the plastic tie and attach it to the upper part of the chopstick using tape to make “arms.”
To keep them upright, use the “warpable spacetime simulator” (playdough) as a base.
Take the small cloth bag and hold it so that the opening is down.
The opening will be the bottom of the shirt.
Cut two small “arm holes” in the front of the shirt. Be careful to cut through the fabric of the front and not along the seams. Cutting through the seams will cause them to rip out.
Cut a “neck hole” in the top of the bag, again being careful not to cut through the seams.
If you’d like, draw a design on the outside of your t-shirt.
Turn the “shirt” inside out and put it on your stick person.
During the experiment
Collecting data
Insert one end of the zip tie into the other to tie the hands of your stick-person together.
Try to turn their shirt right side out. You don’t want an improperly dressed stick person.
Having trouble? Look back at all the ways you listed to turn a shirt inside out. Have you tried them all?
Still having trouble? Ask another group or your teacher. They might be able to look at what you are doing and suggest other ways to try. How were you able to turn the shirt inside out? Draw it here.
Reverse the shirt again.
This time, put the second chopstick in the playdough with your stick person and arrange it so they are "hugging" the pole.
Again, try to turn their shirt inside out. Can you do it in the same way? Why or why not?
Analyzing data
A “constraint” is something that restricts what you are allowed to do or what moves you are allowed to make. What are the constraints in this problem?
Conclusion
What if you needed to turn your pants right side out with your legs tied together? Could you do that? What makes the t-shirt special?