1. Not finding help here? Sign up for a free 30min 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!

Centripetal Acceleration

  1. Oct 6, 2007 #1
    1. The problem statement, all variables and given/known data
    A bicyclist travels in a circle of radius 25.0m at a constant speed of 9.00 m/s. The bicycle-rider mass is 85.0 kg. Calculate the magnitudes of a) the force of friction on the bicycle from the road and b) the net force on the bicycle from the road.


    2. Relevant equations
    F=ma
    m(v^2/r)


    3. The attempt at a solution
    I plugged in the numbers for the force formula and got 275.4 N, I'm assuming that's the net force as its the centripetal force.

    Im unsure how to find the force of the friction however. Any suggestions? (On that note, did I confuse the two?

    -Thanks in advance
     
  2. jcsd
  3. Oct 6, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Start by listing all the forces acting on the bicycle: name them and indicate their direction.

    You did calculate the net force (assuming your arithmetic is correct), but the question asks for the net force from the road, which is not the same thing.
     
  4. Oct 6, 2007 #3
    Ah, so what I found was the force of the bicycle on the road?

    So, the net force on the bicycle on the road would be the reactive force from gravity, making it 9.8 x 85.0 kg, right? (Which is 833N)
     
  5. Oct 6, 2007 #4

    Doc Al

    User Avatar

    Staff: Mentor

    What you found was the net force on the bicycle due to all forces, not just from the road.

    What forces does the road exert on the bicycle? (Consider vertical and horizontal forces separately.)
     
  6. Oct 6, 2007 #5
    According to the answer sheet, the answers I got are correct, but I'll get on thinking about that :)
     
  7. Oct 7, 2007 #6

    Doc Al

    User Avatar

    Staff: Mentor

    How did you answer the questions? You've shown your calculation of the net force on the bicycle. That is one of the answers, but which one? :wink:

    That's the normal component of the force the road exerts on the bicycle, not the net force.

    For your own clarity, I'd still recommend listing the forces acting on the bicycle and their direction.

    Just curious what the answer sheet says.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Centripetal Acceleration
Loading...