🪐 Orbital Motion & Gravitation Simulator
GravitationWhat's happening? For a stable orbit, gravity must equal centripetal force. Too slow = falls inward. Too fast = escapes. This is how satellites stay in orbit.
Gravitation is a high-weightage topic — orbital motion, escape velocity, and Kepler's laws are asked every year.
JEE tests both the mathematical derivations (derive T² ∝ r³) and numerical applications (satellite orbits, escape velocity, gravitational potential energy).
Key formulas
Gravitation & Orbital Motion Formulas
Newton's gravity
F = GMm/r²
M = source mass, m = test mass, r = distance between centres.
Gravitational potential
V = -GM/r
Scalar. PE = -GMm/r. At infinity, V = 0. At surface, V = -GM/R.
Orbital velocity
v = √(GM/r)
Centripetal force = gravitational force. Stable orbit condition.
Kepler's 3rd law
T² ∝ r³, or T² = (4π²/GM)·r³
Time period squared proportional to radius cubed.
Escape velocity
vesc = √(2GM/r) = √2·vorb
Minimum speed to escape gravity — √2 times orbital velocity.
Energy of satellite
E = -GMm/2r
TE = KE + PE. KE = +GMm/2r, PE = -GMm/r, TE = -GMm/2r.
Step-by-step problem solving
How to solve gravitation problems in JEE
- Choose the right formula — use F = GMm/r² for forces, V = -GM/r for potential energies, v = √(GM/r) for orbits.
- Set up the balance — centripetal force = gravitational force for orbits: mv²/r = GMm/r².
- Handle height problems — if object is at height h above surface, r = R + h, not R.
- Use energy conservation — for escape velocity and projectile problems from planet surface.
- Remember: total energy is negative for bound systems — satellites have E < 0, escape requires E = 0.
Common JEE mistakes
What students get wrong
❌ Using r = R instead of R+h
If satellite is at height h, distance from centre = R + h. For low orbits (h << R), r ≈ R is OK, but be careful.
❌ Confusing escape and orbital velocity
vesc = √2 × vorb. If you calculate √(GM/r), you got orbital, not escape. The √2 factor is easy to miss.
❌ Positive potential energy
Gravitational PE = -GMm/r is ALWAYS negative (attractive force). Taking infinity as zero, any finite r gives negative PE.
❌ Assuming geostationary implies equatorial
A geostationary satellite must orbit in the equatorial plane. JEE sometimes asks for the latitude where a non-equatorial satellite can be geostationary — it must be the equator (0° latitude).
How important is Orbital Motion & Gravitation for JEE Main and Advanced?
Orbital Motion & Gravitation is a high-value topic in JEE Physics. Interactive orbital motion simulator. Adjust planet mass, orbit radius, speed. Questions from this chapter test both conceptual clarity and numerical accuracy. In JEE Main, expect direct formula-based problems; in JEE Advanced, expect multi-concept questions combining Orbital Motion & Gravitation with related topics. Mastering the visualization here builds the intuition needed to solve tricky MCQs under time pressure.
FAQs
Gravitation Questions
Why is gravitational PE negative?
We define PE = 0 at infinity. Since gravity is attractive, bringing a mass from infinity to distance r requires positive work from an external agent. But the gravitational potential energy stored is negative: PE = -GMm/r.
Can an object in circular orbit fall down?
No — if it's in a stable circular orbit, the centripetal force from gravity exactly balances the centrifugal effect. The object is in free fall continuously but never collides because the ground curves away at the same rate.
What happens if v > escape velocity?
The object escapes to infinity and still has positive kinetic energy there. Its excess speed (residual velocity) = √(v² - vesc²). The extra energy goes into KE at infinity.
Why does v = √(GM/r) come from force balance?
For a circular orbit, centripetal force mv²/r must equal gravitational force GMm/r². Setting them equal: mv²/r = GMm/r² → v² = GM/r → v = √(GM/r).
Is there a free online Orbital Motion & Gravitation simulator for JEE preparation?
Yes — JEEVisionary's Orbital Motion & Gravitation simulator is 100% free, runs in any browser, and requires no login or download. You can adjust parameters in real time and watch the visualization update instantly, making it ideal for building intuition before solving JEE Physics numericals.
How does the interactive Orbital Motion & Gravitation visualization help in JEE?
The interactive visualization lets you see how changing one variable affects the entire system — something textbook diagrams can't show. JEE frequently tests conceptual understanding through tricky options; using a simulator to build visual intuition helps you eliminate wrong choices faster during the exam.
Can I use this Orbital Motion & Gravitation simulator on mobile during revision?
Absolutely. JEEVisionary's concept lab simulators are fully responsive and work on phones, tablets, and desktops. The touch-friendly sliders let you explore parameters during bus rides, breaks, or quick revision sessions — no app install needed.
Try this
Quick exercise with the simulator
Step 1: Set all sliders to their default positions and observe the baseline visualization for Orbital Motion & Gravitation.
Step 2: Change only one parameter at a time. Before moving each slider, predict what will happen — then check if you were right.
Step 3: Try to find the extreme case — what slider value makes the output maximum or minimum? This is exactly how JEE tests your understanding.
Avoid these traps
Common mistakes
Consuming without acting
Most people do: read the entire page and close the tab without doing anything. You should do: pick one action from the "What to do next" section and complete it today.
Not verifying with official sources
Most people do: trust any website (including this one) as the final authority. You should do: check the linked official portal for dates, fees, eligibility, or document rules before making decisions.
Bookmarking instead of executing
Most people do: save 20 tabs "for later" and never return. You should do: write one next step on paper right now, then close extra tabs.
Before you leave
Revision checklist
- I can explain the key relationship in Orbital Motion & Gravitation without looking at formulas.
- I tested at least 3 different parameter combinations in the simulator.
- I can predict what happens when each variable increases or decreases.
- I solved at least one JEE PYQ from this topic and verified my approach.
- I noted any concept I found tricky in my error log for revision.