In this experiment, middle school and high school students use their PocketLabs learn about angular velocity -- the rate of change of angular position of a rotating body.
This experiment corresponds with NGSS unit "K - Forces and Interactions: Pushes and Pulls."
Learn more about motion and inertia in this PDF from Hooked on Science.
TOPICS: Angular Velocity, Momentum, Inertia
- Tape your PocketLab to the back of a swivel chair, close to the y-axis.
- Select the ANGULAR VELOCITY setting
- Sit in the swivel chair.
- Tuck in your feet (so they don't touch the ground) and pull your arms close to your chest.
- Ask a friend or classmate to spin you in the swivel chair.
- As you are spinning, stretch your arms out from your chest.
- Does it feel faster or slower?
- Examine your PocketLab data. Were you actually spinning faster or slower?
- Stretch your arms in different directions -- including all the way up, parallel to your body.
- Stretch out your feet.
- Spin in different directions.
- Start a spin faster and slower than the original spin.
- Hold a heavy object in your lap.
- When you stretch out your arms, hold something heavy in one hand. Try the other. Try both.
What is angular velocity?
When a figure skater spins, the skater positions her or his arms to control the speed of the spin -- the angular velocity. As you stretch your arms and feet, you distribute your mass across a larger area, spinning more slowly.
The angular momentum of the skater is always conserved, no matter the positioning of the arms, and can be represented by the equation --
L = Iw
-- where L is angular momentum, I is moment of inertia and w is angular velocity.
The moment of inertia is an object’s resistance to change in angular velocity and is related to the distribution of the object’s mass.