SSC CGL 2025 Tier-I · 12 September 2025, Shift 2 · General Awareness · Question 25 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 13 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

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

(a)Mass
(b)Gravitational pull
(c)Orbital velocity
(d)Atmospheric drag

Answer

Why

Correct — C. A satellite is in continuous free fall. Gravity pulls it towards Earth, but its sideways speed carries it forward so that it keeps missing.

At the right speed, the orbital velocity v = √(GM⁄r), gravity supplies exactly the centripetal force for a circle of radius r. With almost no air to slow it, no engine is needed → option (c).

Why the others are wrong

(a)
Mass — The satellite's mass cancels out. In v = √(GM⁄r), M is Earth's mass, so a heavy satellite and a light one at the same height orbit at the same speed.
(b)
Gravitational pull — Gravity alone would pull the satellite down. It provides the centripetal force, but the orbit holds only when the satellite also has the right sideways speed, the orbital velocity.
(d)
Atmospheric drag — Atmospheric drag works against an orbit. It slows low satellites and makes their orbits decay, which is why the International Space Station has to be reboosted periodically.

Concept

For a circular orbit, gravity must supply the centripetal force: GMm⁄r² = mv²⁄r, which gives v = √(GM⁄r), with r measured from Earth's centre.

Close to Earth's surface this is about 7.9 km/s. Higher orbits need less speed, and a body launched at escape velocity, about 11.2 km/s from the surface, leaves Earth's gravity altogether.

Because the satellite's own mass m cancels, orbital velocity depends only on Earth's mass and the orbit's radius.

Key facts

Orbital velocity for a circular orbit: v = √(GM⁄r), with r measured from Earth's centre.
Orbital velocity near Earth's surface is about 7.9 km/s, against an escape velocity of about 11.2 km/s.
Orbital velocity does not depend on the satellite's mass.
Atmospheric drag makes low orbits decay, so the ISS needs periodic reboosts.

Study next

Geostationary versus Sun-synchronous orbitsEscape velocity: v = √(2GM⁄R)Kepler's third law: orbital period and radius

Common traps

Choosing gravitational pull because it holds the satellite: without the right sideways speed, gravity brings it down.
Thinking a heavier satellite must fly faster: the satellite's mass cancels out of the orbital-speed equation.

Here the physics of an orbit is asked as a single quantity, and GA Q.17 of this same shift works the same GM⁄r² relation the other way, asking what a 1% cut in Earth's radius does to g.

Orbit types and their uses are asked at 15 Sep 2025, 16:00, GA Q.12 (Sun-synchronous versus geostationary orbits) and 12 Sep 2025, 16:00, GA Q.16 (PSLV and the orbits it serves).

Related PYQs

No directly related past PYQ was found.

Topic: Economic Scene — all 144 SSC CGL questions on it, every solved shift.