Gravitation: notes and previous year questions

Free notes for every topic in gravitation, with the key formulas and real JEE and NEET questions solved step by step.

Newton's Law of Universal GravitationOne pull for apples and moons: F = Gm₁m₂/r², the inverse-square law, the constant G, centre-to-centre distances, pairs of forces and adding pulls as vectors.
Acceleration due to Gravity and Its VariationWhere g = GM/R² comes from, and how g changes going up, going down, and with latitude on a spinning Earth.
Gravitational Field and PotentialThe field E = GM/r², shells and spheres, potential energy U = −GMm/r, potential V = −GM/r, E = −dV/dr, adding potentials, and solving with energy.
Kepler's Laws of Planetary MotionOrbits are ellipses, equal areas in equal times, and T² ∝ a³: Kepler's three laws, why they follow from gravity, and how to weigh a planet.
Escape VelocityHow fast to launch something so it never comes back: v_e = √(2GM/R) = √(2gR) ≈ 11.2 km/s, what it depends on, escape versus orbit, and why the Moon has no air.
Satellite Motion – Orbital Velocity, Time Period and EnergyHow fast satellites move, how long they take to go round, their energy (1 : 2 : 1), launch energy, geostationary and other orbits, and weightlessness.