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: Centripetal Force and maximum speed

  1. Nov 24, 2005 #1
    A motorcyclist is approaching a hump-backed bridge, as shown in the diagram. The bridge forms part of a circle of radius r = 14.4 m. The combined mass of the motorcycle and rider is 141 kg. Calculate the maximum speed in m s-1 at which the rider could travel without leaving the road at the top of the bridge.

    How do i go about workin this one out without knowing Fmax and [tex]u\mu[\tex] coeff static friction. Thanks in advance
     
  2. jcsd
  3. Nov 24, 2005 #2

    mezarashi

    User Avatar
    Homework Helper

    If it's not given, I guess you get the pleasure of assuming that it is negligible.

    Apply conservation of energy: kinetic energy will be less at the top of the hump.

    Check if the velocity is less than which is required for circular motion.
     
  4. Nov 24, 2005 #3

    Päällikkö

    User Avatar
    Homework Helper

    What is the force keeping him on the road? It's not friction.

    EDIT: Just seconds slower than mezarashi :smile:
     
    Last edited: Nov 24, 2005
  5. Nov 24, 2005 #4
    so mgh=0.5mv^2
    and v=16.8
     
  6. Nov 24, 2005 #5

    mezarashi

    User Avatar
    Homework Helper

    Sorries! >.<
     
  7. Nov 24, 2005 #6

    mezarashi

    User Avatar
    Homework Helper

    You have the car coming at a certain velocity. Apply the conservation equation.

    KE1 + PE1 = KE2 + PE2

    The potential PE1 is zero, we consider ground. The potential at PE2 is mgh. We know KE1, find KE2. Use KE2 in your next step.
     
  8. Nov 26, 2005 #7
    cheers mate mezarashi
    its best to consider the moition using that equation
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook