# Homework Help: Oscillatory Motion

1. Sep 2, 2008

### sheri1987

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

The moment of inertia for an arm or leg can be expressed as I = amL2, where a is a unitless number that depends on the axis of rotation and the geometry of the limb and L is the distance to the center of mass. Say that a person has arms that are 27.80 cm in length and legs that are 38.92 cm in length and that both sets of limbs swing with a period of 1.40 s. Assume that the mass is distributed evenly over the length for both the arm and leg.

**Calculate the value of A for the person's arms.

2. Relevant equations

I am not sure of any equations that include Amplitude.

Here is one that relates to the problem, but cannot be used to solve A:

T = 2pi(sqrt(I/mgL))

T= period given (1.4 s)
I = ?
L = given 27.80
g = gravity 9.81
m =?

3. The attempt at a solution

2. Sep 3, 2008

### Kurdt

Staff Emeritus
Are you sure its amplitude they want and not the little constant in the moment of inertia equation?