The two factors that affect an object's momentum are:

1. Mass (m): This is the amount of matter in the object. The more massive an object is, the more momentum it will have at a given velocity.

2. Velocity (v): This is the speed and direction of the object. The faster an object is moving, the more momentum it will have.

Momentum is calculated using the following formula:

Momentum (p) = Mass (m) × Velocity (v)

So, a change in either mass or velocity will result in a change in momentum.