Category Archives: Rotational Dynamics

Torsion Axle

Demo: ME-Q-TA
Pira Index: 1Q 10.20

 Lab Equipment  Directions
  1.  torsion axle
  1.  Move the weights to equidistant points from the axis and set in oscillation.
  2. Note that the period increases as the weights are moved toward the ends of the rods.
  3. The periods of oscillation should vary between 0.5 and 5 seconds.


Rotational Inertia Tapes

Demo: ME-Q-RT
Pira Index: 1Q 10.00

 Lab Equipment  Directions
  1.  rotational inertia tape apparatus
  2. lab stand (short)
  3. 3 finger clamp
  1.  Spin both rolls. Note that the larger roll continues spinning much longer.
  2. Remove an outer clip binder from each side of the rod and attach it to the end of each tape as you hold them in place.
  3. Ask students which they think will hit the table first. Release each tape at the same time. Why did the small roll unwind the fastest?

Rolling Objects

Demo: ME-Q-RO
Pira Index: 1Q 10.30

 Lab Equipment  Directions
  1.  inclined plane
  2. set of rolling objects incorporating different mass distributions and moments of inertia
  3. soup cans
  1.  Roll disc that is weighted in center and compare with one that is weighted evenly around outer edge. Compare with a hollow cylinder of the same diameter. Try cylinders or disks of different diameters and balls of various sizes.
  2. For soup can race roll can of a broth type soup (chicken noodle) alongside a can of cream-type (cream of chicken).

Rotational Inertia and Torque

Demo: ME-Q-RI
Pira Index: 1Q 20.60

 Lab Equipment  Directions
  1.  2 meter sticks (one weighted) attached to a wooden dowel
  2. lab pole
  3. 90 degree clamp
  4. bubble wrapped foam board
  5. telescope clamp
  1.  Set up the equipment as shown with foam board bungied to the end of a cart as a backboard for the falling sticks.
  2. Place the mass near the 100cm end of the weighted meter stick.
  3. Hold both meter sticks horizontally and let them fall at the same time. Which hits first?
  4. Now move the mass up near the 0cm end of the meter stick. Repeat step 3.
  5. Take student predictions as to what point on meter stick the mass should be placed so that both will hit at the same instant.



Demo: ME-Q-LA
Pira Index: 1Q 60.50

 Lab Equipment  Directions
  1.  hand drill
  2. rope
  1.  Make a loop in the rope and tie a knot to secure it.
  2. Tie the other end of the rope to the hand drill.
  3. Rotate the hand drill slowly in a clock-wise direction.


Hoberman Sphere

Demo: ME-Q-HD
Pira Index: 1Q 40.00

 Lab Equipment  Directions
  1.  Hoberman sphere on pulley
  1.  Expand the Hoberman sphere by removing the small clip at the bottom.
  2. Give the sphere a slight push to make it spin slowly.
  3. As it’s spinning, pull on the bottom pull ring and watch the angular velocity change.
Warning: Don’t pull hard enough to collapse the sphere completely-this damages the pulley system.



Demo: ME-Q-GY
Pira Index: 1Q 50.30

 Lab Equipment  Directions
  1.  gyroscopes (2 types)
  2. special base for gyroscope
  3. gyroscope spinner
  4. Edison cell battery
  5. 2 BA leads
  1.  To use the spinner on metal-ringed gyroscope, attach alligator ends of spinner to opposite poles of Edison cell. Hold down spinner button and hold top edge of spinner against wheel of gyro to start the gyroscope spinning. Balance it on the pencil or the ‘tightrope.’
  2. For the strap gyroscope, push strap, teeth facing inward, completely into the gear chamber on bottom of gyroscope.
  3. Holding gyro by the 2 vertical sides of housing, pull strap out quickly.
  4. Balance the depression in the top of the metal axis on the tip of the pencil.


Gyroscopic Stabilizer

Demo: ME-Q-GS
Pira Index: 1Q 50.72

 Lab Equipment  Directions
  1.  gyroscope on rocker cradle
  2. gyroscope spinner
  3. Edison cell battery
  4. rubber band
  5. book
  6. pen or pencil
  1.  Stretch the rubber band across the gyroscope stand. Attach the alligator ends of the spinner to the opposite poles of the Edison cell. Hold down the button on the spinner and hold the top edge of the spinner against the wheel of the gyroscope to start the gyroscope spinning.
  2. Pivot the book on a pen and set the spinning gyroscope on the book. The rocking cradle is meant to simulate the cross section of a boat.
  3. Rock the “boat” and observe the behavior of the gyroscope.