# Homework Help: Biomechanics statics problem

1. Feb 15, 2017

### Lalaland

1. The problem statement, all variables and given/known data
A man deals his bicycle up a 5 percent road at constant speed. Man+bicycle mass=90 kg with mass centre G. 1)Access direction of frictional forces 2) explain why frinctional force in front wheel can be neglected having a const. speed taking front wheel as FBD 3) Find normal forces

2. Relevant equations
Fy=0 Nf +Nr =G
Fx=0

3. The attempt at a solution
Direction is upward
Fy=0 Nf +Nr =G
Fx=0
M= 0. 0.46G= 1.08Nf.
Nf= 375.67N

Now I don't know how to show that friction in front wheel can be neglected

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Last edited by a moderator: Feb 15, 2017
2. Feb 15, 2017

### CivilSigma

I'm not 100% sure, maybe someone else can pitch in, but:

The normal forces in the front wheel can be neglected because F = ma and since the front wheel is at a const. speed, a = 0 which implies summation of Fx = 0. Therefore friction force must be zero.

This should also apply to the back wheel, ( but I'm not entirely sure if it will have a=0 since it is connected to a gear...)

Also, your calculations are unclear to me in (3), so I can't provide feedback there.