Answer: both mass and velocity
Step-by-step explanation:
Momentum is defined as the product of mass (m) and velocity (v) of a moving body. Hence, momentum is expressed as mv. The unit of momentum is kilograms metre per second (kgm/s).
For instance:
A bullet having a small mass of 0.01kg moving with a velocity of 10000m/s and a heavy ball of mass 100kg moving with a small speed of 1m/s have the same momentum.
Thus, both mass and velocity affect momentum.