Which best describes the purpose of a controlled experiment?

The crank oa rotates in the vertical plane with a constant clockwise angular velocity ω0 of 5.6 rad/s. for the position where oa is horizontal, calculate the force under the light roller b of the 10.6-kg slender bar ab.

What is created when solids,liquids,an gases mix with one another

What are the north and south poles of a solenoid change with?