Question

Which of the following are in equilibrium?
A disc that is speeding up and is spinning up.
A baseball that is at rest and has a constant angular velocity.
A turntable that is at rest and is spinning down.
A tire that has a constant velocity and is spinning up.
A wheel that has a constant velocity and is spinning down.
A football that is slowing down and is spinning up.
A merry-go-round that is at rest and is not rotating.
A planet that moves along a perfectly circular orbit at a constant speed.