Added momentum?
 

R1. Base hit to right field, with R1 going to 3rd. Right fielder has a weak arm, and the throw ends up rolling on the ground past third base. Third baseman chases after the ball, gloves it before the ball has gone out of play, then his momentum carries him and the gloved ball past an out-of-play line. The ball would have gone out of play had the third baseman not carried it out. I'm pretty sure this is still a case of added momentum.

In Fed, dead ball one base.

OBR & NCAA if player maintains body control,the ball remains alive alive.

BRD Section 42

You would be wrong, under pro interpretation.

First, the concept is called "subsequent push" not "added momentum".

Second, "subsequent push" does not involve a ball that is "gloved" and "carried" out of play. A subsequent push occurs when a ball, "remains on the playing field, and is subsequently kicked or deflected, causing the ball itself to enter DBT..." (J/R pg. 32, 1997 ed.)

Third, under OBR, subsequent push, as a rule interpretation, ONLY comes into play after a pitch or an in-contact throw by a pitcher. It is used to determine whether the base award will be one base or two bases.

In your play, under OBR, "(i)f (the third baseman) had secured possession while on the playing field and then stepped into dead ball territory without falling," the ball would remain live. (JEA).