The distance doesn't depend on the mass.
keep distance with moving objects.
a moving objects momentum
Momentum
Momentum depends on mass and velocity.
Velocity tells us the speed at which an object is moving and the direction in which it is moving.
They would be traveling at the same speed. Two objects moving with the same velocity must be moving in the same direction and at the same speed. The reason for this is because velocity is speed in a specified direction. Another way to say that is to say that velocity is speed with a direction vector. It is a physical quantity with magnitude and direction. Two objects moving with the same speed could be moving toward a head-on collision. Or they could be moving along convergent, divergent or skewed paths. Not so with two objects that have identical velocities. They are moving on the same or on parallel courses, and they are moving at the same speed.
momentum
uniform motion
If you have no velocity, then you aren't moving.
By definition, it would have the same speed and direction as the compared object. This can be evidenced by the two objects having an unchanging spatial relationship: i.e. the objects remain the same direction and distance from each other.
Velocity is a measure of an object's speed and direction of motion. It describes how fast an object is moving and in which direction it is moving.
When all forces are balanced, the object can either be moving at a constant velocity or be at rest. But because you asked for balanced forces on a moving object, it is moving at a constant velocity.