Calculate A for Person's Arms in Oscillatory Motion

AI Thread Summary
To calculate the value of A for a person's arms in oscillatory motion, it's essential to understand the moment of inertia formula I = amL², where 'a' is a unitless constant related to limb geometry. Given the arm length of 27.80 cm and a swing period of 1.40 s, the relationship between period, moment of inertia, and mass needs to be clarified. The user expresses confusion about whether the problem is asking for amplitude or the constant 'a' in the moment of inertia equation. The relevant equation for the period T = 2π(sqrt(I/mgL)) cannot directly solve for A without knowing the mass distribution. A clear understanding of these relationships is crucial for solving the problem effectively.
sheri1987
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Homework Statement



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.



Homework 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 =?

The Attempt at a Solution



I'm just really confused on how to go about this problem? Any advice?
 
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Are you sure its amplitude they want and not the little constant in the moment of inertia equation?
 
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