Physics · Class 11 · Chapter 7
Gravitation
11 lessons 83 min 2 simulations
One force pulls a mango off its branch and holds the Moon in its orbit. This chapter starts from Kepler's three laws of planetary motion, arrives at Newton's inverse-square law of gravitation, measures G, and then uses the law to find g at any height or depth, gravitational potential energy, the escape speed, and the speed, period and energy of a satellite.
What the exam asks
NEET asks for g at a height or depth, the ratio of weights at two places, escape speed and orbital speed (ratio √2), orbital period from Kepler's third law, and the kinetic, potential and total energy of a satellite. Marks are lost by measuring distance from the surface instead of the centre, using 1 − 2h/R when h is not small, forgetting that g falls both above and below the surface, and giving a satellite positive total energy.
Lessons
11 lessons · 83 min
1Kepler's lawsNCERT §7.1, §7.26 min2The law of areasNCERT §7.26 min3Universal law of gravitationNCERT §7.36 min4The gravitational constantNCERT §7.46 min5Acceleration due to gravityNCERT §7.56 min6g above and below the surfaceNCERT §7.610 min 1 sim7Gravitational potential energyNCERT §7.76 min8Escape speedNCERT §7.86 min9Earth satellitesNCERT §7.910 min 1 sim10Energy of an orbiting satelliteNCERT §7.106 min11Chapter reviewMust-know facts, traps and formulas15 min