Final answer:
In physics, the lower-case 'g' typically stands for the acceleration due to gravity, while the upper-case 'G' refers to the universal gravitational constant, which is a key part of Newton's law of universal gravitation.
Step-by-step explanation:
In the context of the formula GM / p^2, the letter g usually stands for the acceleration due to gravity. This is sometimes noted in formulas and equations related to physics, particularly when discussing gravitational forces. For example, when discussing the force exerted on an object due to gravity, g represents the constant acceleration objects experience when falling towards Earth, which is approximately 9.8 meters per second squared (m/s^2). However, the letter G in the same context refers to the universal gravitational constant, which is a fixed value that describes the strength of the gravitational force between two objects. This constant is denoted as G and has a value of approximately 6.674 × 10^-11 N(m/kg)^2. It's important to distinguish between the lower-case g and the upper-case G since they represent different concepts in physics.