Why does a satellite continue in its orbit around the Earth? Identify the fundamental cause that maintains the satellite's circular (or near-circular) motion.

Introduction / Context:
Orbital mechanics explains how satellites remain in continuous “free fall” around Earth. Understanding which force acts as the required inward pull clarifies many topics in dynamics, from banking of roads to planetary motion.

Given Data / Assumptions:

• Satellite moves in a near-circular orbit around Earth.
• Neglect air resistance at orbital altitude.
• Earth’s gravitational field provides an attractive inverse-square central force.

Concept / Approach:
Uniform circular motion requires a radial inward force equal to m * v^2 / r. In orbital motion, this necessary inward (centripetal) force is supplied by gravity: F_g = G * M_E * m / r^2. The orbital speed adjusts so that the gravitational pull exactly matches the centripetal requirement, keeping the body in orbit rather than falling straight down.

Step-by-Step Solution:

Verification / Alternative check:
Because the satellite is continually “falling” toward Earth while moving tangentially fast enough, the path curves around Earth. No outward “real” force is needed; the so-called centrifugal force is a fictitious force observed only in a rotating frame.

Why Other Options Are Wrong:

• “Gravitational force” alone is incomplete; the correct physical role is that it acts as the centripetal force.
• Centrifugal force is an apparent force in a non-inertial frame, not the cause in an inertial frame.
• Air drag at orbital altitudes is negligible and opposes motion, not sustains it.
• “None of these” is unnecessary because a precise correct option exists.

Common Pitfalls:
Confusing centrifugal with centripetal; thinking satellites need continuous thrust (they do not for closed orbits, aside from station-keeping adjustments).

Final Answer:
Centripetal force provided by Earth’s gravity