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

• A_lilah
In summary, the question is asking for the smallest radius of an unbanked track that a bicyclist can travel around with a speed of 29 km/h, given a coefficient of static friction of 0.29 between the tires and the track. The equations used to solve for this radius include the coefficient of static friction formula and the net force formula. The solution involves finding the maximum static friction force and setting it equal to the centripetal force equation, then solving for the radius. The final answer is dependent on the mass of the object, the speed, and the coefficient of static friction.
A_lilah

## 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!

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.
$$f=\frac{m{v^2}}{r}$$

solve to get r.

Ah...
thank you for the help!

## Related to Can Static Friction Exist on a Moving Bicycle on a Flat Track?

"Friction Contradiction" is a term used to describe the phenomenon where two surfaces that are in contact with each other experience both frictional forces and relative motion at the same time.

"Friction Contradiction" is caused by the fact that friction is a force that opposes relative motion between two surfaces, but it is also dependent on the roughness and adhesion of those surfaces. So, even if there is relative motion between two surfaces, the roughness and adhesion can still create frictional forces that act against that motion.

## Why is "Friction Contradiction" important to understand?

"Friction Contradiction" is important to understand because it can affect the accuracy of calculations and predictions in various fields such as engineering, physics, and materials science. It is also important to consider in real-life situations, such as when designing machines or creating friction-reducing materials.

## How can "Friction Contradiction" be minimized or eliminated?

"Friction Contradiction" can be minimized or eliminated by using lubricants, such as oil or grease, between the two surfaces to reduce the effects of roughness and adhesion. Additionally, using smoother and more polished surfaces can also help reduce the frictional forces.

## What are some real-life examples of "Friction Contradiction"?

Some real-life examples of "Friction Contradiction" include the sliding of tires on a road, the movement of gears in a machine, and the rubbing of two body parts against each other, such as in the joints of the human body. It can also be observed when trying to slide a heavy object across a rough surface, where there is both relative motion and frictional forces acting at the same time.

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