Assertion (A) : Two artificial satellites having different masses and revolving around the Earth in the same circular orbit have same speed. Reason (R) : The speed of a satellite is directly proportional to the radius of its orbit.

Assertion (A) is true because the orbital speed of a satellite in a circular orbit is independent of its own mass [t1, t2]. The speed is determined by the formula v = sqrt(GM/r), where G is the gravitational constant, M is the mass of the central body (Earth), and r is the orbital radius [t3, t6]. Since both satellites are in the same circular orbit (same r), they must have the same speed regardless of their different masses [t1, t9]. Reason (R) is false because the orbital speed is inversely proportional to the square root of the radius (v ∝ 1/√r), not directly proportional to the radius [t5, t6]. As the radius increases, the required orbital speed actually decreases to maintain a stable circular path [t1, t9]. Therefore, while the assertion is a correct physical observation, the reason provided is mathematically incorrect.