Distinguish between: (A) Real and pseudo forces.

                                  (B) Conservative and non-conservative forces. 

                                  (C) Contact and non-contact forces.

                                  (C) Inertial and non-inertial frames of reference.

Define coefficient of restitution and obtain its value for an elastic collision and a perfectly inelastic collision.

Discuss the following a special cases of elastic collisions and obtain their exact or approximate final velocities in terms of their initial velocities.

(i) Colliding bodies are identical. Initially at rest,

$$\begin{gathered} \overrightarrow{v_1}=\overrightarrow{u_2} \\ \overrightarrow{v_2}=\overrightarrow{u_k} \end{gathered}$$