6000 kg train moving 5 m/sec to east collides with 5000 kg train moving 3 m/sec to west. what is their velocity

They all deal with hard evidence(scientific)

Aand b antarctica is a north pole.  field lines enter earth near the north pole.the magnetic pole near antarctica is a north pole.compasses point toward a magnetic pole that is a north pole.field lines circle earth from east to west.a compass can lead a hiker to the geographic north pole.

In atoms, the electron carries a negative elementary or unit charge; the proton carries a positive charge. the two types of charge are equal and opposite. in an atom of matter, an electrical charge occurs whenever the number of protons in the nucleus differs from the number of electrons surrounding that nucleus.

The inference is supported by evidence in the graph is this is an exothermic reaction where the total release of energy equals a + c.