Link to Rotational Energy lab



Pasco Rotary Motion Sensor
  • Author: Jeff Lawlis
  • Lab diagram and derivation
  • Allows one to calculate the moment of inertia of the platform and object using Pasco's Rotary Motion Sensor. You can use the included metal ring or rod with adjustable weights, or for added fun, try building a cage out of balsa wood, glue it to the platform, and find the moment of inertia of a (hard-boiled) egg. I don't have a full lab procedure at the moment, but I use masses between 10 - 60 g and the smallest radius setting on the spindle.
more inquiry rotational mass from lab. Mitch Johnson
My students (ap) are pretty intuitive about torque after lining them at the door with a pneumatic closer and take turns opening the door close and far from the hinges. It is pretty obvious that force and radius are all that is needed to rotate something. We then do 5 runs changing the hanging mass and change the point mass radii on the turn table and run again with 5 more masses and measure the acceleration. the 5 slopes of the line is the resistance to turning "rotational mass". it becomes obvious that the rotational mass is different with the point mass radii so those 5 rotational masses ar e graphed against radius squared and the slope is the point masses and the y intercept is the rotational mass of the apparatus. We save the data and revisit energy by graphing potential vs rotational velocity and the slope is half the rotational mass found earlier. The same equipment is used to develop the parallel axis equation by moving a disk in from the out side to the middle. We also do transfer of linear momentum to rotational by using large masses on a pendulum that crashes into a clay catcher after a propane torch burns the string at the bottom of its path. Not to mention the flying pigs. My students and from the ap test results, most have trouble on rotation. I count the extra time as review because we are constantly moving back to linear motion from the tension in the string of a falling mass to conservation of energy. Not surprisingly my students beat the ave score on the rotation problem on the test.


Torque
Algebraic proof that the center of mass can be used when calculating the torque of an object around a fulcrum:

  • Author: Chris Becke
  • Derivation
  • Provides an algebraic proof that torque around a fulcrum can be calculated using the center of mass of a uniform rod instead of concerning yourself with the amount of mass that hands on either side. (I've often found myself saying "you can just use the center of the entire rod -- the math works out and everything cancels" without actually providing a proof. So I sat down and provided a proof.)


Wheels Within Wheels
Demonstration of the amusement park ride called "mind scrambler", "Octopus", Tilt-a-Whirl", etc. where a rider rides in a circle while rotating around an axis.

  • Author: Paul Beeken
  • Demonstration
  • Shows how to model the motion using parametric formulas and use vector analysis to examine the relationship between the displacement, velocity and acceleration vectors. It has an interactive component that can be viewed in the new freely available Mathematica CDF player .

Angular Momentum

Powerpoint with links to YouTube Video Examples - some links are dead bc they are linked to Interactive Physics files on my computer.

more Angular momentum from linear Mitch Johnson
I HAVE no handouts as I teach by modeling physics where the lab comes first and the equation comes from the lab. Then we use the equation todo homework.
let me clarify the lab.
the pendulum is around 300g I use one string through a loop on the lead mass. (it is from a specific heat kit). Because it is one string they only have to burn through one string and the mass will fall into the clay receiver (no bounce). My students always must come up with the independent and dependent. WE draw on linear and when ever there is a collision we use momentum so it is natural for them to invoke momentum before the collision as an independent. we have already derived rotational mass from experiment weeks before and keeping with momentum the dependent is Iw. the slope of the graph is kgm/s/kgmm/s which is 1/m which is the inverse of the radius to the receiver. moving the radius to the other side gives mass*velocity*radius=Iw I have read studies that indicate that humans have a much more difficult time remembering rotation than translational motion so I try to do as many rotational labs as possible. any good rotational platform with low friction can have a clay catcher. I do not want to fire a cannon into the clay as it is not as much fun. They have a great time and laugh at whom ever burns themselves.
let me know if you have any other questions.

Rotational Kinematics Activity - Dan Burns
An interactive lecture demonstration lab introduction to rotational kinematics. Students measure alpha for a turntable after turning it off, then predict time to stop at a different RPM and change in angle. Other alphas are measured when changing turntable RPM. A turntable connected to speakers under a camera is used. A lot of fun happens as students here LPs at 45 RPM and the sound after the turntable power is turned off. You also can hear secret backwards messages and do some DJ scratching if you don't care about scratching your record. This is the student handout, email me with questions: dburns@lgsuhsd.org


Rotational Inertia Lab - Dan Burns
A basic lab where students determine the rotational inertia of an object that is spun by a falling weight. This is a new lab and I will update it before I do it again. It did work well in its present form so I decided to post it anyway. This is the student handout, email me with questions: dburns@lgsuhsd.org



Rotational Derby Lab - Dan Burns
This is my take on the Conceptual Physics lab where students roll different objects down a ramp to see what is the fastest. This is the student handout, email me with questions: dburns@lgsuhsd.org


Energy of Rotation Lab - Dan Burns
Students roll a billiard ball down a ramp made out of adjustable shelving bracket holder. They predict the velocity at the bottom of the ramp, predict the ball's acceleration, and where it will land on the floor. A challenging lab for Mech. C students. This is the student handout, the lab is so old I no longer have an editable file for it, unless you have a copy of Wordstar 5.5! Email me with questions: dburns@lgsuhsd.org



Angular Momentum Lab - Dan Burns
This lab is written for a rotational apparatus like PASCO or Vernier, I have PASCO. I highly recommend having a rotational motion system from one of these vendors for rotational dynamics. This is the student handout, email me with questions: dburns@lgsuhsd.org


Rolling and Slipping - Posted by Dan Burns
This handout is helpful for rolling and slipping problems.