This textbook has been specifically developed on the directives of National Education Policy (NEP 2020) and is as per latest curriculum of B. Sc. Physics (First Semester) for the University of Lucknow. The book comprised of Four units. Unit I cover important topics such as Galilean Transformation of Space and Time, Newton's Laws of Motion, Michelson - Morley experiment, Postulates of Special Theory of Relativity, Concepts of Gradient, Divergence and Curl, Stoke's Curl Theorems and Pseudo Forces in Rotating Frame. Unit II highlights the Elastic and Inelastic Collisions in 1D and 2D, Concept of Centre of Mass Frame, Moment of Inertia Principles and their Applications to Different Shaped Bodies, Elasticity and Elastic Constants, Torsion Pendulum, Bending of Beam and Cantilever. Unit III includes Reduction of Two Body Central Force Problem to One Body Problem, Centre of Mass Motion, Motion of Planets and Satellites in Solar System, Kepler's Laws of planetary Motion, GPS and Motion Four Galaxy. Unit IV covers S.H.M., Damped and Forced Harmonic Oscillations, Sharpness of Resonance, Plane Progressive Waves, Standing Waves, Phase and Group Velocity.