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⚛️ Physics  ·  Gravitation  ·  NEET & JEE

Two satellites move in the same circular orbit around Earth, one having twice the mass of the other. Their orbital speeds are:

Answer: equal.

  • A equal
  • B the heavier one is faster
  • C the lighter one is faster
  • D the heavier one is slower

Correct answer: A. equal

Explanation: Orbital speed v = √(GM/r) is independent of the satellite mass, so they are equal.

Variation of g with Height and Depthgg_surfaceAbove surface: g ∝ 1/r² (falls off curving down)Below surface: g ∝ r (falls off LINEARLY)Earth's surface (r = R)centre (r=0): g=0g is MAXIMUM exactly at the surface - it decreases in both directions, but by different laws

g is maximum at Earth's surface; going up, it falls off as 1/r² (inverse-square); going down, it falls off linearly with depth (since only the mass enclosed within radius r contributes), reaching zero at the centre.

Concept context

Universal gravitation, orbital mechanics, gravitational potential, and escape velocity.

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