11. Momentum & Impulse

In which of the following processes is the momentum $p$ of the object conserved?

Which statement must be true for the momentum $p$ of a system to be conserved?

A rifle of mass $M$ fires a bullet of mass $m$ with velocity $v$. After firing, which has more momentum: the rifle or the bullet?

In projectile motion, is there any point along the trajectory where the velocity vector $\overrightarrow{v}$ and the acceleration vector $\overrightarrow{a}$ are parallel to each other? If so, where does this occur?