Unit – I B

Newton’s Law of Gravitation Problems:

Formulae

Gravitation Unit 1 B 08

  1. Calculate the force of attraction between two metal spheres each of mass 90 kg, if the distance between their centres is 40 cm. Given G = 6.67 x 10-11 N m2/kg2 .
  2. Find the gravitational force of attraction between the moon and the earth if the mass of the moon is 1/81 times the mass of earth. G = 6.67 x 10-11 N m2/kg2 , radius of moon’s orbit is 3.58 x 105 km. Mass of the earth = 6 x 1024 Kg.
  3. Two bodies of masses 5 kg and 6 x 1024 kg are placed with their centres 6.4 106 m apart. Calculate the force of attraction between the two masses. Also find the initial acceleration of two masses assuming no other forces act on them.
  4. A sphere of mass 40 kg is attracted by another spherical mass of 15 kg by a force of 9.8 x 10-7 N when the distance between their centres is 0.2 m. Find G.
  5. A sphere of mass 100 kg is attracted by another spherical mass of 11.75 kg by a force of 19.6 x 10-7 N when the distance between their centres is 0.2 m. Find G.
  6. Distance of a planet from the earth is 2.5 x 107 km and the gravitational force between them is 3.82 x 1018 N. Mass of the planet and earth are equal, each being 5.98 x 1024 kg. Calculate the universal gravitation constant.
  7. Three 5 kg masses are kept at the vertices of an equilateral triangle each of side of 0.25 m. Find the resultant gravitational force on any one mass. G=6.67 x 10-11 S.I. units.


Answers:

  1. 3.377 x 10-6 N
  2. 2.213 x 1020 N
  3. 48.85 N, 9.77 m/s2, 8.142 x 10-24 m/s2
  4. 6.533 x 10-11 Nm2/kg2
  5. 6.672 x 10-11 Nm2/kg2
  6. 6.676 x 10-11 Nm2/kg2
  7. 4.621 x 10-8 N towards the centroid

Solutions of above problems will be uploaded soon on this page

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