In physics, what does 'g' represent?

In physics, 'g' specifically denotes the acceleration due to gravity, which is the rate at which objects accelerate towards the Earth when in free fall, absent other forces. This acceleration is approximately 9.81 m/s² near Earth's surface, meaning that for every second an object falls, its velocity increases by about 9.81 meters per second. This value is crucial in understanding motion and forces acting on objects in a gravitational field.

The other choices refer to different physical concepts: the gravitational force constant is associated with the universal law of gravitation, the mass of an object is a measure of the amount of matter it contains, and the energy of a system refers to the ability to do work, which encompasses various forms of energy like kinetic and potential energy. Each of these terms plays an important role in physics but does not represent the acceleration due to gravity, which is what 'g' indicates.