# Homework Help: Moment of inertia wheel and bug

1. Dec 15, 2011

### Jdanka

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

There is a wheel with spokes rotating on a horizontal axis about its center.

the Wheel has a w(omega) of 6∏ and a radius of .04meters

there is a bug on one of the spokes at exactly 1/2 radius or .02meters. the bug has a mass of .005kg.

2. Relevant equations
not really sure which equations to use, but here are a bunch that will most likely be helpful
Icm of rod = 1/3mL^2
Icm of wheel = Mr^2
v=w/r
a=σ(alpha)*r

3. The attempt at a solution
The questions are
A) find the angular speed of the bug

B) find the linear speed of the bug

these are just the first couple questions of many but any help would be appreciated.

2. Dec 15, 2011

### LawrenceC

"the Wheel has a w(omega) of 6∏ and a radius of .04meters"

If you are specifying the rotational speed of the spoked wheel, you need more units.

Six pi radians in what amount of time?

3. Dec 15, 2011

### Jdanka

there is no time given, but what might be helpful to know is that the wheel has a negative acceleration (was not given the amount). also incase it wasn't clear the wheel is rotating vertically

unfortunately I have a very difficult physics teacher. I dont need the answer in numbers nor do i want it, but I would like to know how to solve this

4. Dec 15, 2011

### LawrenceC

If the bug is clinging to a spoke, then it is moving with the wheel. That tells you its angular speed. To determine its linear speed, you already have the equation posted to do that.

5. Dec 15, 2011

### Jdanka

Is it really that simple to find angular velocity? i thought for sure that I would have to use some form of energy to find it using I. and as far as linear velocity goes I thought because it was not on the outside of the wheel that it would have a different velocity than a point on the wheel

6. Dec 15, 2011

### LawrenceC

The angular speed of the bug is the same as the angular speed of the wheel. For the linear speed, you have the formula V = omega * r. You typed it incorrectly in your original post.