Originally Posted by

**saurab dulal**
**harold 14370**wrote:

The frictional force on any point of the tip is equal to the normal force, divided by the surface area of contact multiplied by the coefficient of friction.

i never found anywhere the defination of frictional force as you said. rather i found that frictional force is the component(horizantal) of contact force(the force due to electostatic interaction betwen molecules incontact )and normal force is another component of same contact force.frictional force is equal to normal force multiplied with coefficient of friction.also if i and my refrence book are wrong in about the understanding of friction force then help me where can i find the exact defination like you said.

also about the point, as i know c.g always lies on a point in general defination and in case of top it is on the same vertical axes with tip of top which i called point and i think it doesnt matter whether you call it point or dimensional.your explanation doesnt concern with my question.