Why is the variable p used for momentum?

Answer 1

Before the word "momentum" was decided upon, they used "impetus". Impetus comes from the latin, "petere," to go towards or rush upon. Petere is where the p comes from.

Rather usefully p is also the mirror of q (the reaction to a momentum) which makes it rather memorable.

Answer 2

The variable "p" is commonly used to represent momentum in physics because it stands for "momentum" in equations. It is a convention that has been adopted over time for consistency and ease of communication among scientists and researchers in the field of physics.