Another word for momentum is impetus.
Impetus refers to the driving force or energy that propels an object or action forward. In physics, momentum specifically relates to the quantity of motion an object has, depending on its mass and velocity. However, in a broader context, impetus can be used to describe the motivation or force behind actions and decisions in various fields, such as business or personal development. So while momentum is often used in a scientific context, impetus serves as a suitable synonym in more figurative situations.