Remove advertisements
Results 1 to 2 of 2

Thread: Conservation of angular momentum GIF

  1. #1
    Jon
    Jon is online now Jon has agreed the Seller's Terms of Service
    Administrator Jon's Avatar
    Join Date
    Jan 2012
    Location
    Colorado, USA
    Posts
    7,694
    Thanks
    1,451
    Thanked 720 Times in 427 Posts

    Conservation of angular momentum GIF

    Conservation of angular momentum GIF.


    https://s3-us-west-1.amazonaws.com/h...r_momentum.gif

    How is it working? Physicists, please correct me if I have the wording wrong here:

    The man and the wheel essentially act as a closed system. An externally-applied torque (the standing man spinning the wheel by hand) produces vertical angular momentum in the wheel. When the wheel is turned horizontal, the man must spin counter to the wheel's rotation, to conserve angular momentum.

    One interesting usage is in spacecraft telescopes. Such spacecraft need to be pointed in a very specific direction. If a spacecraft must be rotated by very small amounts, they can do so with an electric motor attached to a flywheel, called a reaction wheel. When the rotation of the spacecraft changes, the reaction wheel is used to counter-rotate the spacecraft proportionally.

    Reaction wheel from Kepler spacecraft:


  2. The Following User Says Thank You to Jon For This Useful Post:

    PJs (01-09-2017)

  3. #2
    mklotz mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    511
    Thanks
    16
    Thanked 1,055 Times in 385 Posts
    "An externally-applied torque (the standing man spinning the wheel by hand) produces vertical angular momentum in the wheel."

    The angular momentum is the scalar moment of inertia of the wheel times the vector angular velocity of the wheel and is thus a vector aligned with the vector direction of the wheel's spin along the axle axis. So when he spins it the angular momentum is horizontal, not vertical.

    The seated man is using the bicycle wheel as a reaction wheel to torque himself around exactly as the telescopes (and other satellites) use their reaction wheels to orient themselves.

    Reaction wheels produce a smoother motion than control jets and have the advantage that they never run out of fuel as long as the solar paddles can keep charging the batteries.


    Post your reply!
    Join 20,941 of us and get our 50 Must Read Homemade Tools eBook free.



    50 Must Read Homemade Tools
    ---
    Regards, Marv


    Home Shop Freeware
    http://www.myvirtualnetwork.com/mklotz

  4. The Following 3 Users Say Thank You to mklotz For This Useful Post:

    Jon (01-09-2017), PJs (01-09-2017), Seedtick (01-15-2017)

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Remove advertisements