How o astronomers gather information to establish the hubble law?

A-4.60 μc charge is moving at a constant speed of 6.80×105 m/s in the +x−direction relative to a reference frame. at the instant when the point charge is at the origin, what is the magnetic-field vector it produces at the following points.

Free runners jump long distances and land on the ground or a wall. how do they apply newton’s second law to lessen the force of impact?

Gunpowder residue is most likely to show up where on a shooters hands