Both federal child labor laws and Massachusetts state law concur that the minimum age to work is 14 (with some exceptions). But child labor laws in each state may vary regarding the minimum age to work and which permits are needed. When there is a conflict between federal and state laws, the strictest law will apply. Although 14 is the official age Massachusetts youth generally begin working, there are exceptions.
The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid body is a tensor that determines the torque needed for a desired angular acceleration about a rotational axis.
Example #1: Find the moment of inertia of a stick (length L and mass M) of uniform density, rotating about an axis through its center of mass. The illustration shows a picture of this stick. The chunk of mass, dm is exaggerated in size for clarity.