Nuclear fission explained on the basis of liquid drop model

When a liquid drop is suitably excited it may oscillate in a variety of ways.The liquid drop becomes  a prolate spheroid,a sphere,an oblate spheroid,a sphere,a prolate spheroid again,and so on.The restoring force of its surface tension always returns the drop  to spherical shape,but the inertia of the moving liquid molecule causes the drop to overshoot sphericity and go to the opposite extreme of distortion.
Nuclei exhibit surface tension,and so can vibrate like a liquid drop when in an excited state.They also are subject to disruptive forces due to the mutual repulsion of protons.When a nucleus is distorted from a spherical shape,the short range restoring force of surface tension must cope with the long range repulsive force as well as with the inertia of the nuclear matter.If the degree of distortion is small,the surface tension can do this,and the nuclear vibrates back and forth until it eventually loses its excitation energy by gamma decay.If the degree of distortion is too great,however,the surface tension is unable to bring back together the now widely separated groups of protons,and the nucleus splits into two parts.