Observations of spiral galaxy show a major axis of 1.5x105 ly and a minor axis equal to 80% of the major axis. if the radial velocity of a gas cloud located in the spiral arms is calculated at 156 km/s, what is the true rotational velocity of the cloud?

Gravity, from the center of mass of the box, extending downward normal force, from the floor under the box, extending upward, equal to gravity push force, acting at a point on the box, extending in the direction of motion friction, acting at any point on the box directly opposite the push, extending directly opposite to the motion

An em wave does not require a medium, while a mechanical wave does.