Q1: The total time of collision and restitution of two bodies, is called

ANS:D - all the above.

Let's break down each option: a) Time of collision: This refers specifically to the duration during which two bodies are in contact with each other during a collision. It usually begins when the bodies first make contact and ends when they cease to be in contact. b) Period of collision: This term is less commonly used but could be interpreted similarly to the time of collision. It suggests the duration over which the collision occurs, including the time during which the bodies are in contact and possibly any subsequent interaction immediately following the collision. c) Period of impact: This term encompasses both the time of collision and the time during which the bodies are rebounding or undergoing restitution after the collision. It includes the entire duration of interaction between the two bodies, from initial contact through to the completion of restitution. Therefore, the correct option "all the above" indicates that each of the terms (time of collision, period of collision, and period of impact) relates to the total time of collision and restitution of two bodies, although "period of impact" is the most comprehensive and widely used term to describe this concept.