By definition, force F is the rate of change of momentum p. Thus, F = dp/dt Now, momentum is the product of mass m and velocity v. If mass is constant, F = m x dv/dt F = ma (a = dv/dt) where a is...
It could be anything you want as long as you and the audience understands it.
Convention, however, usually shorthands force as 'F'.
Newton's 2nd law:
F=ma
Force is the acceleration of a...