We’re used to seeing things spin, from yo-yos to ballet dancers. However, we usually see them spin in one direction. What happens when something spins in more than one direction at once? In this activity we will use cardboard tubes marked with an “x” and “o” to show what happens when something spins in two directions at once. Though on its surface this experiment seems simple, the results are unexpected and exciting.
Student Guide
Twists & Turns
Experimenting with force on spinning objects
When a tube spins in two directions at once, what does it look like?
This resource was originally published in PhysicsQuest 2010: Force!
When a tube spins in two directions at once, what does it look like?
- White cardboard tube
- Marker
Intro
Before the Experiment
- Draw a rolling log
Draw a rolling log, what forces are acting on it that make it roll? Now draw these forces and an arrow indicating which direction the log is turning.
- What things can you think of that spin in two directions at once?
What things can you think of that spin in two directions at once? Draw them and indicate which directions they are spinning.
- What happens when something is spinning in two directions?
What happens when something is spinning in two directions? Does it spin the same speed at every point in its spin or do the two directions of spinning add up to the spinning you see?
Setting Up
- Cut the tube into two sections
Cut the tube into two sections, one 1.5” long and one 2.5” long.
- Mark each end
For each piece put an “x” on one end and an “o” on the opposite side at the opposite end.
During the Experiment
- Hold the tube by the middle and spin it back and forth
Hold the tube by the middle and spin it back and forth. Around which axis is it turning?
- Now pick another axis and turn the tube around that
Now pick another axis and turn the tube around that.
- How many axes can you think of around which you can turn the tube?
How many axes can you think of around which you can turn the tube?
- Set the longer tube on the table with the “x” up and on the right side
Set the longer tube on the table with the “x” up and on the right side.
- Push on the “x” so that the tube both rotates and spins
Push on the “x” so that the tube both rotates and spins.
- Start with the tube in the same position, but this time spin it by pushing on the side without the “x"
Start with the tube in the same position, but this time spin it by pushing on the side without the “x."
- Set the tube on the table with the “o” up and on the right side and push on the “o” to spin and rotate the tube
Set the tube on the table with the “o” up and on the right side and push on the “o” to spin and rotate the tube.
- Start with the tube in the same position as in step 4, but this time spin the tube by pushing on the side without the “o”
Start with the tube in the same position as in step 4, but this time spin the tube by pushing on the side without the “o."
- Now repeat steps 1-5 with the shorter piece of tube
Now repeat steps 1-5 with the shorter piece of tube.
Analyzing Data
- What were your results?
What were your results?
- When you pushed on the tube to get it started, what forces were acting on it? Think about the force of your finger, the table etc.?
- When the tube was spun by pushing on the “x,” what did you see? What about what happened when you pushed on the “o” to start it spinning and rotating? Draw it:
- Did the same thing happen when you pushed on the blank end? Draw it:
- Why do you think you could sometimes see more than one “x” or more than one “o” at the same time?
Why do you think you could sometimes see more than one “x” or more than one “o” at the same time even though there was really only one “x” or one “o” on the tube?
Conclusion
- What do you think would happen if you had the “x” and “o” on opposite ends but on the same side of the tube?
What do you think would happen if you had the “x” and “o” on opposite ends but on the same side of the tube?
- What differences did you see between the short tube and the long tube?
What differences did you see between the short tube and the long tube?