Hannah Emmerson of Bermuda Sandcastle fame fire spinning on Southlands Beach (Photo:  Chris Ingham)
Home >> AP Physics I >> Gravitation and Orbits >> Vertical Circles
Universal Gravitation >>

3.2 - Motion in a Vertical Circle

Objectives:
  • To be able to consider the changes in the forces acting on an object that is moving in a vertical circle and relate this to observable phenomena
Picture
Picture
Animation of vertical circular motion.  Shows how the tension in the string varies

LAB WORK

Investigative Work

  1. What is the minimum speed necessary to keep water in a bucket from spilling.  Demonstrate this using the VideoPhysics app
  2. Whirling a ball attached to a rope around your head and then releasing it.  What is the maximum range of the ball?
  3. Same idea, but this time whirling in a vertical circle!
  4. Analysis of vertical circular motion using the VideoPhysics app.  Could you use a newtonmeter?
  5. Measuring the speed of a conical pendulum and comparing with the theory.  Use either lightgates or VideoPhysics app.
There are a few standard lab assignments that are used for this topic.  The moments (torque) experiments are easily set up and generally involve masses, string, newtonmeters and planks of wood.  The circular motion lab involves whirling a rubber bung on a string around your head to demonstrate the centripetal force equation....!

Additionally, it is nice to attempt a project-based lab:
  • estimating how the tension in the spoke of a bicycle wheel vary as a function of speed - this could also involve the relative position of the spoke to the ground.
  • measuring the speed of a bucket of water whirling in a vertical circle using an ipad, what is the minimum speed required to keep the water in the bucket?
  • measuring the range of a whirling ball on a rope that is let go at the top of its flight - involves measuring the speed of the ball (either with stopclocks or an ipad), and some projectile kinematics.
  • how does the turning moment of a yacht vary as the angle of heel is increased?  Is there a limit - assuming that the force on the sails is applied horizontally? Extension: how does the tension in the shrouds vary?
  • how does the tension in a spinnaker guy vary as the boat goes from a run to a reach?  Could this be measured?
Suggested activities: 
  • Find a data table on car stopping distances.  Students determine the coefficient of friction from this data, then create a new table of car speed against minimum turning radius.
  • A pendulum of (say) 2 N weight is swinging.  At the bottom, it is neither speeding up or slowing down.  What is the tension of the string?
Universal Gravitation >>

Other Resources

PhET Simulation - Balancing Act
PhET Simulation - Gravity and Orbits
$\sum_{k=1}^n k = \frac{n(n+1)}{2}$