In an elastic collision of two billiard balls, which of the following quantities remain conserved during the short time of collision of the balls a) kinetic energy b) total linear momentum Give a reason for your answer in each case.
During collision no external force is acting on the balls, therefore total linear momentum of the system of two balls is always conserved. During collision when the balls are in contact, there may be deformation, hence some kinetic energy of system will be transformed to potential energy of system and consequently kinetic energy will not be conserved. Important point: Though kinetic energy of system will not be conserved but total energy of the system will be conserved
