Can Static Friction Exist on a Moving Bicycle on a Flat Track?

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
2 replies · 4K views
A_lilah
Messages
52
Reaction score
0

Homework Statement



What is the smallest radius of an unbanked (flat) track around which a bicyclist can travel if her speed is 29 km/h and the coefficient of static friction between tires and track is 0.29?



Homework Equations



coefficient of static friction = (f of maximum static friction / Normal force)

fnet = ma = m * v^2 / r

The Attempt at a Solution



If an object is moving, isn't their just kinetic friction? I get that the normal force is the acceleration, but how can there possibly be a maximum static friction at this point?

Here's what I've got:

29km/h = 8.0556 m/s

.29 = fstatmax / a, therefore a = fstatmax / .29

Fnet = m* a = m * (v^2 / r)
Fnet = a = v^2 / r
fstatmax / .29 = (8.0556)^2 / r

Thanks for any help!
 
Physics news on Phys.org
If an object is moving, isn't their just kinetic friction?

In case of tyres, the bottom-most point is instantaneously at rest. That's why static friction.

f=0.29Xmg.
[tex]f=\frac{m{v^2}}{r}[/tex]

solve to get r.
 
Ah...
thank you for the help!