## Newton’s Law of Gravitation Problems:

### Formulae 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.