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Exam level4 past questions

Satellite motion and orbital parameters

Satellite motion involves understanding orbital velocity, time period, escape velocity, and the specific conditions for geostationary orbits.

Why this shows up in the exam

You will solve NEET questions on satellite launches, orbital mechanics, and related calculations.

How NEET tests this

Statement analysis · 2 QsNumericalApplication

Learn the idea

A geostationary orbit is a circular orbit whose period equals Earth’s rotation (24 h). The radius is fixed by the balance of gravity and centripetal force, giving r = (G M T²/4π²)^(1/3). The satellite’s own mass drops out.

🧠 Memory hook: G‑M‑T = ‘Gravity‑Mass‑Timer’ – the three things that set the size of a geostationary clock‑orbit.

Get this one clearly and it pays off every single time it shows up in the paper. 🎯

Formulas & facts to keep ready

  • Gravitational force: F = G M m / r²
  • Centripetal force for circular motion: F = m v² / r
  • Orbital speed: v = √(G M / r)
  • Period–radius relation: T = 2π √(r³ / G M)
  • Geostationary condition: T = 24 h → r = (G M T² /4π²)^(1/3)
  • Escape speed from Earth’s surface: v_esc = √(2 G M / R)

How to approach it

  1. 1Read the question and note which quantity (r, v, T, or v_esc) is required
  2. 2Write the appropriate formula from the key ideas, keeping only G, M, T (or R) as needed
  3. 3Insert the given numerical values, watch unit consistency (seconds, metres)
  4. 4Solve algebraically; if satellite mass appears, cancel it out
  5. 5Check that the answer matches the physical condition (e.g., 24 h for geostationary)

Worked example — watch it click

Choose the correct statement from the following: The radius of the orbit of a geostationary satellite depends upon:

  • A)mass of the satellite, its time period and gravitational constant.
  • B)mass of the satellite, mass of the earth and the gravitational constant.
  • C)mass of the earth, mass of the satellite, time period of the satellite and the gravitational constant.
  • ✅mass of the earth, time period of the satellite and the gravitational constant.

The concept behind this problem

The question asks which parameters actually appear in the formula for r; recognizing that m disappears tests the core derivation of the period‑radius relation.

Step by step

  1. 1For geostationary satellite: orbital radius r = (GMT²/4π²)^(1/3).
  2. 2This depends on mass of Earth (M), time period T (24 hours for geostationary), and gravitational constant G.
  3. 3It does NOT depend on satellite mass m (cancels out in force equation).
  4. 4Therefore option (d) is correct.

Watch out

Students often mistakenly include the satellite’s mass as a factor determining the geostationary radius.

Common slip-ups that cost marks

  • •Assuming the satellite’s mass influences the orbital radius – it cancels in the force balance
  • •Confusing orbital period with angular speed; remember T = 2π/ω
  • •Mixing altitude above Earth’s surface with the orbital radius measured from Earth’s centre

🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.

Practise it

These are real questions from past NEET papers that test this exact idea.

Question 1 of 4NEET 1995

Choose the correct statement from the following: The radius of the orbit of a geostationary satellite depends upon:

Push further

More challenging

12 harder questions built from the past papers above — a step up in difficulty, with distractors designed so you can't get there by elimination. Written and checked by our reviewers, not from a real paper.

Question 1 of 12

A space shuttle is in a stable orbit around Earth. An astronaut performs an Extravehicular Activity (EVA) and accidentally lets go of a tool. What happens to the tool?

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