Advertise on Bikeforums.net



User Tag List

Results 1 to 12 of 12
  1. #1
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    I am clueless when it comes to solving this

    This was a test question today. What pisses me off is that I have solved a problem almost exactly like this before, a few months ago. I can't remember at all how I did it
    "A car is driving in a circuit with a radius of 35m, what is the max velocity it could be traveling at? Coefficient friction is .453".

    Any ideas? Something to jump start my mind?
    C://dos
    C://dos.run
    run.dos.run

  2. #2
    Hazardous Taerom's Avatar
    Join Date
    Jun 2005
    Location
    Quarantine
    My Bikes
    2005 Trek Liquid 55, 2009 Haro Mary SS
    Posts
    727
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    What kind of car is it?

  3. #3
    del dot
    Join Date
    Sep 2006
    Location
    Santa Cruz CA
    My Bikes
    Tour Easy
    Posts
    209
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by phantomcow2
    This was a test question today. What pisses me off is that I have solved a problem almost exactly like this before, a few months ago. I can't remember at all how I did it
    "A car is driving in a circuit with a radius of 35m, what is the max velocity it could be traveling at? Coefficient friction is .453".

    Any ideas? Something to jump start my mind?
    If the track surface is level (rather than banked), then the normal force on the car is equal to its weight mg (where m=car's mass, g = gravitational field). Maximum force of friction is the coefficient of friction times the normal force.

    Meanwhile, the force needed for the car to navigate the circle is its mass m times the centripetal acceleration v^2/r.

    The car is driving at the maximum possible speed when the needed force (mv^2/r) equals the maximum possible force (mg times the coefficient of friction).

    So set these two expressions equal, notice that the car's mass m cancels out (which is good, since they didn't give it to you), and solve for v.

  4. #4
    I play in the street. nobrainer440's Avatar
    Join Date
    Jul 2005
    Location
    College: K-State; Home: Overland Park, KS
    My Bikes
    2005 Allez Triple, 1971 Schwinn Varsity Fixed Gear Conversion
    Posts
    977
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    (max. force due to friction) = (coeff of friction) * (normal force)

    f = m*a

    a = v^2 / r

    I think those should do it.

  5. #5
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,117
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(s)
    Quote Originally Posted by Taerom
    What kind of car is it?
    and what color?
    Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
    Quote Originally Posted by colorider View Post
    Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

  6. #6
    Hazardous Taerom's Avatar
    Join Date
    Jun 2005
    Location
    Quarantine
    My Bikes
    2005 Trek Liquid 55, 2009 Haro Mary SS
    Posts
    727
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jsharr
    and what color?
    Yeah, cuz red cars are always the fastest!

  7. #7
    Senior Member DannoXYZ's Avatar
    Join Date
    Jul 2005
    Location
    Saratoga, CA
    Posts
    11,507
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    This is the same problem as the carnival ride where you slide up a vertical wall on the spinning platform. At a certain speed, you stick to the wall and don't slide down... NoBrainer's equations are all you need... Don't get hung up on the mass units as they cancel out... good way to double-check your work as well. Write out each step and include the units and show your work...

  8. #8
    I-M-D bell curve of bikn'
    Join Date
    Dec 2005
    Location
    NC mountains
    My Bikes
    06' Jamis Eclipse in the making.
    Posts
    2,929
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Does the car have abs brakes and how heavy is the driver?
    Ego Campana Inflectum of Circuitous

  9. #9
    Infamous Member chipcom's Avatar
    Join Date
    Sep 2005
    Location
    Ohio
    My Bikes
    Surly Big Dummy, Fuji World, 80ish Bianchi
    Posts
    24,373
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Taerom
    Yeah, cuz red cars are always the fastest!
    Don't be silly. What is playing on the radio at the time?
    "Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey

  10. #10
    la vache fantôme phantomcow2's Avatar
    Join Date
    Aug 2004
    Location
    NH
    Posts
    6,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    . The worse part is that I wrote down nobrainers equations, I got that far. If I had spent all of 3 more minutes thinking about this I would have solved it. I feel like I ran a marathon but stopped 20ft before the finish line.
    C://dos
    C://dos.run
    run.dos.run

  11. #11
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,117
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(s)
    Quote Originally Posted by chipcom
    Don't be silly. What is playing on the radio at the time?
    This on an endless loop.
    Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
    Quote Originally Posted by colorider View Post
    Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.

  12. #12
    Banned. Turboem1's Avatar
    Join Date
    Aug 2006
    Location
    Long Island
    My Bikes
    Lemond Reno
    Posts
    883
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If my calculations are correct, when this baby hits eighty-eight miles per hour... you're gonna see some serious ****.

Posting Permissions

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