## Unit – I B |

## Newton’s Law of Gravitation Problems:

### Formulae

- 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 m^{2}/kg^{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 m^{2}/kg^{2}, radius of moon’s orbit is 3.58 x 10^{5}km. Mass of the earth = 6 x 10^{24}Kg. - Two bodies of masses 5 kg and 6 x 10
^{24}kg are placed with their centres 6.4 10^{6}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. - 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. - 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. - Distance of a planet from the earth is 2.5 x 10
^{7}km and the gravitational force between them is 3.82 x 10^{18}N. Mass of the planet and earth are equal, each being 5.98 x 10^{24}kg. Calculate the universal gravitation constant. - 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:

- 3.377 x 10-6 N
- 2.213 x 1020 N
- 48.85 N, 9.77 m/s2, 8.142 x 10-24 m/s2
- 6.533 x 10
^{-11}Nm^{2}/kg^{2} - 6.672 x 10
^{-11}Nm^{2}/kg^{2} - 6.676 x 10
^{-11}Nm^{2}/kg^{2} - 4.621 x 10-8 N towards the centroid

good questions please publish the method also

Solutions are available at https://hemantmore.org.in/foundation/science/physics/newtons-law-gravitation/7220/

WELL DONE BUT I AM BECOMING MORE CONFUSED

Visit https://hemantmore.org.in/physics/gravitation/

Very mst

Can't we use sin30 in last question to get the two resultants and the add them to get the total force towards the centroid???

Use the following link and refer solved problems

https://hemantmore.org.in/foundation/science/physics/newtons-law-gravitation/7220/