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!

Non-uniform circular motion, [stunt Car inside a ring]

  1. Oct 20, 2011 #1
    1. The problem statement, all variables and given/known data
    [PLAIN]http://img695.imageshack.us/img695/3864/unled1dxu.jpg [Broken]


    2. Relevant equations

    F=(mv^2)/r

    3. The attempt at a solution
    NetForce=0
    N-W=0

    ===
    A free body diagram of the car at the bottom would just incorporate a downwards W force and an upwards N force together equalling 0, wouldn't it?
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Oct 20, 2011 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Those are the correct forces, but why would they add to 0? The car is accelerating!
     
  4. Oct 20, 2011 #3
    Accelerating as in change of direction?
    I would think that the bottom of the loop is the maximum speed of the car, past that half the car begins to decelerate, no?
     
  5. Oct 20, 2011 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Yes. It's executing circular motion, so what kind of acceleration must exist?
    You are told that the speed is constant.
     
  6. Oct 20, 2011 #5
    I think I got it. Knowing constant velocity did help.
    Given the top of the loop circumstances, the only forces acting upon the car are N and W, together they equal the centripetal force.
    Keeping the same velocity at the bottom, the N and W act against each other, but the centripetal force still has to equal that of when it was at the top in order to maintain circular motion.
    Apparently N takes on a greater value to compensate I guess and I get an answer of 20.1

    How's my reasoning? Is this the same reasoning with planes flying in a circular loop as well?
     
  7. Oct 20, 2011 #6

    Doc Al

    User Avatar

    Staff: Mentor

    Good!
    Similar considerations apply to anything moving in a vertical circle. (Of course, the speed of the plane will not necessarily be constant.)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Non-uniform circular motion, [stunt Car inside a ring]
Loading...