In the absence of significant local mass anomalies, in which direction is Earth’s gravitational acceleration vector $g$ always directed at a point near Earth’s surface?

• A. Toward the center of the Earth (radially inward)
• B. Always tangent to Earth’s surface in the direction of Earth’s rotation
• C. Always vertically upward, away from Earth’s surface
• D. Always toward the North Pole, parallel to Earth’s axis of rotation

Answer: (A)

Verified step by step guidance

1. Understand that Earth's gravitational acceleration vector \( \mathbf{g} \) represents the direction and magnitude of the gravitational force per unit mass experienced by an object near Earth's surface.
2. Recall that gravity is a central force caused by Earth's mass, which pulls objects toward the center of mass of the Earth.
3. Recognize that in the absence of local mass anomalies (like mountains or dense rock formations), the gravitational acceleration vector points along the line connecting the object and Earth's center.
4. Therefore, the vector \( \mathbf{g} \) is directed radially inward, meaning it points toward the center of the Earth at any point near the surface.
5. This direction is not tangent to the surface, upward, or aligned with Earth's rotation axis; it is always directed toward Earth's center due to the nature of gravitational attraction.