What specific physical quantity ensures a satellite maintains its orbit without continuous propulsion?

Question

What specific physical quantity ensures a satellite maintains its orbit without continuous propulsion?

1. A. Mass
2. B. Gravitational pull
3. C. Orbital velocity (Correct answer)
4. D. Atmospheric drag

Correct Answer

Option C — Orbital velocity

Detailed Solution & Explanation

The correct answer is Orbital velocity.

Key Points

• A satellite stays in orbit because its orbital velocity gives it exactly the tangential speed at which it falls around the Earth rather than into it.
• Gravity supplies the centripetal force; the orbital speed supplies the sideways motion. Balanced, they need no continuous propulsion.
• The relation is v = √(GM/r), so the required speed falls as the orbit rises.

Additional Information

• Low Earth orbit needs roughly 7.9 km/s; escape velocity from the surface is about 11.2 km/s, the speed at which an object leaves Earth's gravity entirely.
• A satellite is in continuous free fall, which is why its occupants experience weightlessness — gravity has not vanished, it is simply unopposed.
• Atmospheric drag is the reason low orbits decay and satellites need occasional reboosts; a geostationary orbit at about 35,786 km has a 24-hour period.

प्रश्न (हिन्दी में)

कौन सी विशिष्ट भौतिक मात्रा यह सुनिश्चित करती है कि उपग्रह निरंतर प्रणोदन के बिना अपनी कक्षा बनाए रखे?

1. A. द्रव्यमान
2. B. गुरुत्वाकर्षण खिंचाव
3. C. कक्षीय वेग
4. D. वायुमंडलीय खिंचाव