A1000-kg car approaches an intersection traveling north at 20.0 m/s. a 1200-kg car approaches the same intersection traveling east at 22.0 m/s. the two cars collide at the intersection and lock together. ignoring any external forces that act on the cars during the collision, what is the velocity of the cars immediately after the collision?

Explanation:

During the collision of two cars there is no external force on this system

so the total momentum of two cars will remains conserved

so we will have

now when two cars collide inelastically then they will move together after collision

so we have

because if the tool that you are using is not balanced it there would be false mass.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.