The first scientists to suspect the existence of dark matter were puzzled because galaxies

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 the momentum of a 2 kg object moving at 15 meters per second

Which best represents the law of conservation of mass ?