The spherical balls of mass 10 kg each are paced 10 cm apart. Find the gravitational force of attraction between them.

Two satellites A and B move round the earth in the same orbit. The mass of B is twice the mass of A.

Which of the following quantities remain constant in a planetary motion (Consider elliptical orbits) as seen from the sun.

Four particles having masses m_, 2m_, 3m and 4m are placed at the four corners of a square of edge α. Find the gravitational force acting on a particle of mass m placed at the center.

Three equal masses m are placed at the three corners of an equilateral triangle of side α. Find the force exerted by the system on another particle of mass m placed at

(a) The mid-point of a side,

(b) At the Centre of the triangle.