A vector quantity
Explanation
Acceleration due to gravity ($g$) is the acceleration gained by an object due to the gravitational force exerted by a massive body, such as the Earth. As a physical quantity derived from force, its classification depends on whether it possesses direction in addition to magnitude.
Detailed Analysis:
- Vector Nature: Acceleration is defined as the rate of change of velocity. Since velocity is a vector quantity involving both speed and direction, acceleration is also a vector quantity. Acceleration due to gravity always acts towards the center of the Earth (or the massive body causing the field). Therefore, it has a specific direction and is a vector quantity.
- Distinction from Universal Constant: It is crucial to distinguish $g$ from the Universal Gravitational Constant ($G$). While $G$ is a scalar and remains constant throughout the universe, $g$ varies depending on location (altitude, depth, and latitude). Thus, $g$ is not a universal constant.
- Units: The SI unit of acceleration due to gravity is meters per second squared ($m/s^2$). It is a dimensional quantity, not unitless.
Key Takeaway:
Acceleration due to gravity ($g$) is a vector quantity directed towards the center of the Earth, whereas the Universal Gravitational Constant ($G$) is a scalar quantity.