# Homework Help: Angular Momentum with Bike

1. Aug 18, 2013

### postfan

1. The problem statement, all variables and given/known data

A bike is going clockwise around a circle of radius R (see below). The moment of inertia of each wheel around its center I_cm is NOT negligible. What is the direction of the total Angular Momentum of the bike about the center of the circle (point Q)? Consider when the bike is at the location shown below , and use the directions described in the graph (e.g. vector 2 is pointing to the center of the circle, vector 3 is directed down -perpendicular to the plane-, etc).

CHOICES
1
a vector pointing somewhere between 1 and 2 in quadrant 2
2
a vector pointing somewhere between 2 and 3 in quadrant 3
3
a vector pointing somewhere between 3 and 4 in quadrant 4
4
a vector pointing somewhere between 4 and 1 in quadrant 1

2. Relevant equations

3. The attempt at a solution
I thought it was 3 because the biker was perpendicular to the plane of the circle, but that's wrong. So what is the correct answer?

#### Attached Files:

• ###### bike2.jpg
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2. Aug 18, 2013

### haruspex

I also get number 3. Considering the movement of the bicycle around Q and the rotation of the wheels about their centres separately, the first gives vector straight down while the second points along axis 4.