By an electron revolving in a circular orbit of radius V around a nucleus

CBSE Class 9 CBSE Class 9 Science
1

What is the amount of work done in the following cases? Justify your answer by giving the appropriate reason.

  1. By an electron revolving in a circular orbit of radius V around a nucleus.
  2. By the force of gravity, when a stone of mass ‘m is dropped from the top of a multistoreyed building of height ‘h’.
2
  1. When an electron revolves around the nucleus in circular orbit, a centripetal force is acting inwards while it displaces tangentially at angle of 90° on its circumference as shown, so work done is zero. i.e. W = Fs cos 90°
    image
  2. As the stone is dropped from rest, its potential energy starts converting into KE. Let its speed be v, then from
    image