- #1
kchurchi
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Homework Statement
A uniform sign is nailed into a wall at its top two corners. The nail on the upper-right corner breaks, and the sign begins to rotate about the remaining nail in the upper-left corner. The mass of the sign is 69 kg, L (length) = 1.6 m, H (height) = 2.2 m, and the moment of inertia of the sign about the upper-left corner is 170 kg · m2.
What is the moment of inertia about an axis that is parallel to the one through the upper-left nail but passes through the center of mass of the sign?
What is the angular acceleration of the sign just after the nail breaks?
Homework Equations
Icm (rectangular sign) = [m*(H^2] + L^2)]/12
I(p) = I(cm) + m*d^2
Where d is the perpendicular distance to the axis of rotation
Ʃτ = I*[itex]\alpha[/itex]
?
The Attempt at a Solution
So I am just confused on the second part. Using the first equation that I provided I was able to find the moment of inertia about a parallel axis at the center of mass. For the next part though, I tried using the equation for a mass rotating about a "point" at a certain distance from the center of mass to find this distance. From there I stopped. I don't really know what to do now? I thought of maybe using torque but wasn't sure how.
Any help is appreciated! Thanks :)