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Centre of Mass: The Point That Behaves Like a Particle
Centre of Mass Explained: The Point That Behaves Like a Particle Quick answer: In one line: Centre of Mass — exam-ready notes in one glance. In one…
IIT/NIT/BITS engineering entrance ecosystem.
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Gravitation Bonus: Shell Theorem to GEO Satellites
The side streets of Gravitation: field intensity E = GM/r², the shell theorem, potential inside a planet, true weightlessness, and the geostationary conditions — Part 9 (bonus) of the JEE/NEET Physics Gravitation series.
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Variation of g: Why You Weigh Less at the Equator
How g changes with height, depth and latitude — three formulas, one 15-second free-mark numerical, and how gold traders and mineral surveys quietly use them.
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Satellite Energy: Why Total Energy Is Negative KE Over Two
The −2 : +1 : −1 ratio (PE : KE : E) that solves every satellite-energy question, the halve-the-radius pattern, and why a satellite that loses energy speeds up — plus LIGO's binary inspirals.
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Gravitational Potential Energy: Why the Minus Sign Matters
U = −GMm/r explained: zero at infinity, negative means bound, mgh is its near-surface shadow — with a 3 GJ worked numerical and the sign traps that cost more marks than any calculation.
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Angular Momentum: Gravity Can Pull, It Cannot Twist
Why central forces conserve angular momentum (τ = 0), the L = mvr shortcut for elliptical-orbit speed problems, and how pulsars, satellites and ice skaters all obey the same rule.
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Kepler’s Laws: The 1609 Prediction Machine NASA Still Uses
Kepler's three laws — ellipse orbits, equal areas, T² ∝ r³ — with the 15-second ratio method that turns them into guaranteed marks, and how they discovered Neptune and 5,800+ exoplanets.
Physics cover 4684
Orbital Velocity: Why the ISS Never Falls
Orbital velocity vₒ = √(GM/r) = √(gR) from centripetal-force balance, the r = R+h trap, and why higher satellites move slower — with the √2 link to escape velocity.
Physics cover 4683
Escape Velocity: The Speed That Ends Gravity’s Grip
Escape velocity vₑ = √(2GM/R) = √(2gR) derived from energy conservation, with the Moon worked numerical, the three traps that cost marks, and why the Moon has no atmosphere.