Class 11 Physics - BIHAR
Gravitation
The chapter Gravitation in Class 11 Physics for Bihar Board (BSEB) explores the fundamental force of attraction between any two masses in the universe. Students learn Newton's Universal Law of Gravitation, the concept of acceleration due to gravity (g) and its variation with altitude, depth, and shape of the Earth. The chapter deeply covers Kepler's laws of planetary motion, gravitational potential energy, escape velocity, and the mechanics of orbiting satellites. This is a high-scoring and conceptually vital chapter for the BSEB physics exam, frequently featuring numerical problems and derivation-based long-answer questions.
Start Learning FreeKey Concepts
Newton's Law of Gravitation
Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Acceleration Due to Gravity (g)
The acceleration produced in a freely falling body due to the Earth's gravitational pull, whose standard value is approximately 9.8 m/s² at the surface.
Variation of g
The value of 'g' changes as we go above the Earth's surface (altitude), below the surface (depth), and from the equator to the poles due to the Earth's rotation and shape.
Kepler's Laws of Planetary Motion
Three empirical laws describing planetary motion: the law of orbits (ellipses), the law of areas (equal areas in equal times), and the harmonic law (T² proportional to R³).
Escape Velocity
The minimum velocity required for an object to break free from the Earth's gravitational field and never return, which is approximately 11.2 km/s for Earth.
Important Formulas
Board Exam Info
In the Bihar Board (BSEB) Class 11 Physics exam, this chapter typically carries around 5 to 7 marks. Questions usually include short-answer conceptual questions about the variation of 'g', derivations of escape velocity or orbital velocity, and numerical problems based on Newton's law of gravitation and Kepler's laws.
Frequently Asked Questions
Why does the value of g change from the equator to the poles?
The Earth is not a perfect sphere; it is flattened at the poles and bulges at the equator. Due to this equatorial bulge and the centrifugal force caused by the Earth's rotation, 'g' is greater at the poles than at the equator.
What is the difference between gravitational mass and inertial mass?
Inertial mass is a measure of an object's resistance to acceleration when a force is applied, whereas gravitational mass determines the gravitational force experienced by the object in a gravitational field.
Does a satellite orbiting the Earth have any weight?
Inside an orbiting satellite, objects experience a state of weightlessness. This happens because both the satellite and the objects inside it are in free fall towards the Earth with the same acceleration.
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