Free 186 More Best Homemade Tools eBook:  
Coupon code for 40% off membership: SUMMER24

User Tag List

Results 1 to 2 of 2

Thread: Conservation of angular momentum GIF

  1. #1
    Jon is offline Jon has agreed the Seller's Terms of Service
    Supporting Member
    Jon's Avatar
    Join Date
    Jan 2012
    Colorado, USA
    Thanked 39,242 Times in 11,460 Posts

    Conservation of angular momentum GIF

    Conservation of angular 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:

    Save 40% on Membership

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

    PJs (Jan 9, 2017)

  3. #2
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    LA, CA, USA
    Thanked 6,447 Times in 2,132 Posts

    mklotz's Tools
    "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.

    2,000+ Tool Plans
    Regards, Marv

    Home Shop Freeware

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

    durrelltn (Feb 14, 2022), Jon (Jan 9, 2017), PJs (Jan 9, 2017), Seedtick (Jan 15, 2017)

Thread Information

Users Browsing this Thread

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


Posting Permissions

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