Patterns of problems
6 min read

Gravitation

- It is always better to be prepared. Practice the kind of problems asked in various exams
1
Pattern: Simple problems involving universal law of gravitation.

Description: Any particle of matter in the universe attracts any other with a force varying directly proportional to the product of the masses and inversely proportional to the square of the distance between them.

Question can be asked

  • Problem to calculate the gravitational force between two bodies.
  • Problem to calculate the effect of gravitational force in a system of bodies.
  • Problem to find the distance at which gravitational force acting on any mass is zero.
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2
Pattern: Problem based on superposition principle.

Description: Discuss about net force acting on one mass by number of bodies and the concept of negative mass.

Question can be asked

  • Problem to calculate the force acting on one mass by no. of bodies.
  • To find the gravitational force between the solid spherical bodies of uniform density which have cavities in them.
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3
Pattern: Problem based on variation in the value of acceleration due to gravity.

Description: The value of 'g' depends upon the height and the depth on the earth surface. And also upon the latitudinal position on earth.

Question can be asked

  • To find the value of 'g' at some height above the earth surface.
  • To find the value of 'g' at some depth below the earth surface.
  • To find the variation of 'g' due to the axial rotation of earth.
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4
Pattern: Problem based on gravitational field and gravitational potential
Description: The gravitational potential at a point in a gravitational field is the work done per unit mass that would have to be done by some externally applied force to bring a massive object to that point from some defined position of zero potential, usually infinity.
Question can be asked
1. To find gravitational field due to continuous masses by integration of elemental masses.
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5
Pattern: Problems based on Kepler's law
Description: Kepler's laws of planetary motion state:
  • All planets move around the Sun in elliptical orbits, with the Sun as one focus of the ellipse.
  • A radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time.
  • The square of the time period of revolution of a planet around the sun in an elliptical orbit is directly proportional to the cube of its semi-major axis
Question can be asked
1. To find the relation between the time period and the area swept by the planet on the imaginary orbit.
2. To find the relation between the time period and the radius of the imaginary orbit of planet.
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6
Pattern: Problem based on binary energy and Satellites.
Description: The concept of binary energy is helpful in finding the escape velocity, orbital velocity, time period of revolution of satellites and many more space exploration.
Question can be asked
1. To find the escape velocity and its variation with mass and radius of planet.
2. To find the orbital velocity of satellites.
3. To calculate the time period of revolution of satellites in circular orbits.
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