**Newtonian Law of Attraction :-**

**Every particle of matter attracts every other particle of matter with a force which varies directly as the product of the masses of the particles and inversely as the square of the distance between them .**

Let

**m1****gm**and

**m2****gm**be the masses of the two particles placed at a distance of the

**r****cms**. Then the force of attraction

*between them is such that*

**F***when*

**F varies m1 , m2***is constant .*

**r***when*

**F varies 1/(r.r)***are constant*

**m1 , m2**Therefore by theorem of joint variation

*is given by*

**F**

**F varies (m1m2) /(r.r)**i.e.

**F= gama (m1m2)/(r.r)**where

*is called constant of attraction .*

**gama**So , the

**Newtonian law of attraction is**

**Attraction = gama (product of mass)/(square of distance)****Important :-**

-------- The attraction of a rod

*at an external point*

**AB***is the same as that of the arc of a circle , of like material with center*

**P***and of radius equal to perpendicular from*

**P***on*

**P***, which is intercepted by the lines*

**AB***and*

**PA***.*

**PB**