Aballet student with her arms and a leg extended spins with an initial rotational speed of 0.90rev/s . as she draws her arms and leg in toward her body, her rotational inertia becomes 0.80 kg⋅m2 and her rotational velocity is 4.1rev/s .
determine her initial rotational inertia.

Why does the input force have to be greater than the force needed to lift the bale?

Awheel rotates without friction about a stationary horizontal axis at the center of the wheel. a constant tangential force equal to 82.0 n is applied to the rim of the wheel. the wheel has radius 0.150 m . starting from rest, the wheel has an angular speed of 12.8 rev/s after 3.88 s. what is the moment of inertia of the wheel?

Many machines- including inclined planes such as ramps- increase the strength of the force put into the machine but decrease the distance over which the force is applied.