1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: PLease help me!

  1. Apr 16, 2009 #1
    Pic :http://asia.cnet.com/i/r/2005/dt/39233079/segway_b1.jpg"

    The rider stands on the platform behind the handle bars that controls the forward and backward motion of the vehicle by shifting his/her center of gravity forward and backward. The motor inside the base of the vehicle constantly adjust the torque that is delivered to the wheels in order that the rider does not fall. This question examines the physical principle that makes it possible for someone with no acrobatic skills to ride the segway. Consider a segway on a level street with the mass of the vehicle plus the rider m. When the rider is mounted motionlessly on the segway, the center of the mass of the vehicle plus the rider is located at height, h above the street. The wheels have radius r and their combined moment of inertia is I. Ignore air friction.

    1) Solve for the normal and the static friction forces that the street applies to the vehicle as it accelerates forward with a constant acceleration a on a leveled surface.

    2) How much torque must the motor deliver to each wheel in order to maintain stable motion with constant acceleration a?

    3) How much torque do you need to deliver to each wheel in order to maintain that constant acceleration?

    Please if you solve this with detailed explanation, I will be in forever debt to you. Please help.
    I have no idea
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Apr 16, 2009 #2


    User Avatar
    Homework Helper

    You know how things work here by now don't you? What are your thoughts on how to approach it?

    How's that for a segue to a solution?
    Last edited by a moderator: Apr 24, 2017
  4. Apr 16, 2009 #3
    Here is my force diagram.

    http://img18.imageshack.us/img18/5382/forcediagram.jpg [Broken]

    I am not sure how to start.

    F_firc = u*F_n

    F_n = Mg;
    Last edited by a moderator: May 4, 2017
  5. Apr 16, 2009 #4
    I have the same problem...not sure how to start this one....
  6. Apr 16, 2009 #5
    u in physics w/ jones
  7. Apr 16, 2009 #6
    yeah lol. pretty stumped on this segway problem...looking for some insight
  8. Apr 16, 2009 #7
    f this test
  9. Apr 17, 2009 #8


    User Avatar
    Homework Helper

    Well what needs to be in balance?

    Did I hear you say that the sum of the torques will need to be imbalanced in order to accelerate?

    From your drawing you have 2 centers of mass to worry about, though you can combine them into one. The Segway and the human. But let's say they are combined and it's located above the platform that the rider stands on as you have drawn. The way you've defined θ it looks like is going to be Ms - the mass of the system times g times cosθ times the height of the CoM above the platform that determines the torque that needs to be balanced.

    So how do you figure the counterbalancing torque and the torque required to accelerate the system will be supplied through the axle?
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook