==== Kick Off Questions ====
  - What are the conditions for angular momentum conservation?
  - What is the difference between rotational and translational angular momentum?
  - What is the right-hand rule for angular momentum?
  - If a system includes two objects, but nothing is rotating can it have angular momentum? Why or why not?

====== Project 13A, You spin me right around, part 1 ======
<WRAP info>
====Learning Concepts====
  * Angular Momentum
  * Choosing an appropriate system
  * Rotational Kinetic Energy
  * Conservation of Momentum
  * Conservation of Angular Momentum

</WRAP>
<WRAP info>

==== Project 13A: Kickoff Questions ====

  * What is angular momentum conservation?
  * What is the difference between rotational and translational angular momentum?
  * What is the right-hand rule for angular momentum?
  * If a system includes two objects, but nothing is rotating can it have angular momentum? Why or why not?


</WRAP>

{{183_projects:p1000804.jpg?500}} 

Last time on post-apocalypse now: Your group of scientists have begun work on putting together an alternative power generator based on a merry-go-round ride from a playground. Suddenly a wormhole opens in the middle of the Thunderdome and four strangers clad in 2020's clothing emerge. They relay that they have been trapped for years in a place called the Marvel universe by someone named Korath and that they eventually escaped. Time does not flow at the same rate in the Marvel universe, and so they are shocked to find themselves in a post-apocalyptic Earth. They quickly develop a plan to rewrite history by combining the generator your scientists have been working on with exotic technology they stole from the Marvel universe to create a time machine that can send a small metallic item back in time. But first you need enough energy to power the time machine. 

The merry-go-round ride has one bar moving from the center of the ride to a point at the edge of the ride. You also have available to you seven 5kg weights and each of you has a backpack. The uniform density disk that comprises the ride is 300kg and has a radius of 2.5m. Your team which is working on the roundabout consists of 4 members. You are informed by the lead scientist of the new arrivals "Flo Rida" that the ride needs to achieve an energy of either 1036 Joules or 6500 Joules in order to generate enough electricity to send what you have decided is a paperclip back in time. 

But as plans are put in place the Thunderdome comes under attack from boar tigers. Luckily as a defensive precaution, a pit has been dug to surround the roundabout and been set on fire (boar-tigers are afraid of fire).

Powering the time machine to 1036 Joules will send the paperclip back to the original satellite launch and make critical machinery fail and stop the apocalypse. Powering the time machine to 6500 Joules will send the paper clip back to a time in which you knew Carver was driving his car before an accident and will cause the vehicle to explode preventing Carver from launching the satellite or any future satellites. The future (or the past) is in your hands. Choose wisely.

 {{course_planning:problem_13_diagram.jpg?250|}}

==== Wrap-up Questions ====

  * What type or types of angular momentum did your system have before the collision? How about after the collision?
  * Was linear momentum of your system conserved? Why or why not?
  * Could you use conservation of kinetic energy here? Why or why not? If not, how much was lost or gained?
  * Did your results make sense or what you expected? Is it possible to reach an energy of 6500 J? Why or why not?
  * How many sandbags would be required if they were moving at 3 m/s to reach the higher energy level?
  * How do we know angular momentum is conserved here? Doesn't the axle generate a torque?
  * If there were a way to apply a constant 10 N force at the edge, what force would show up at the axle?
      * Could the 10N force be used to get the required rotational energy? Why or why not. If it could, qualitatively, describe this process.