Question

In Case of elastic energy we say restoring force equal to force applied by us so no K.E and energy is P.E BT if force by bus equals restoring then how it moves ??and also Work done =CHange in K.E can we apply here

Answer 1

Elastic energy is only Applicable to Elastic bodies such as Rubber.
As bus is not an elastic body therefore the concept of restoring force can't be applied here.
You can apply work energy theorem stated by you to calculate the work done by the bus provided that you know the final and initial velocity.

Hope you get your answer.

Hol