Name the force which provides the centripetal force in the following cases :

An earth's satellite is kept moving in its orbit.

Name the force which provides the centripetal force in the following cases :

Railways tracks are banked on curves.

Name the force which provides the centripetal force in the following case:

A stone tied at one end of a string is being whirled.

Name the force which provides the centripetal force in the following case:

An electron is revolving round a nucleus.

When a car takes a turn round a curve, a passenger sitting in a car tends to slide. To which side does the passenger slide? Why?

What is the necessity of banking the road? Which factors the angle of banking depends upon?