NEET Physics-03 Heat, Gases, Oscillations and Waves

Why does heat sometimes seem to “disappear” into work—and other times stubbornly stay as temperature? This book builds the thermodynamics and waves toolkit you need for NEET-style physics, with a sharp focus on concepts, sign conventions, and the classic traps that cost marks. You’ll start by nailing thermal equilibrium and the zeroth law, seeing exactly why temperature is a single well-defined number and how a thermometer works as the “third body.” You’ll also learn to separate temperature from heat, and to think clearly about adiabatic vs diathermic boundaries—especially in tricky setups like gases separated by insulating and conducting partitions. From there, you’ll master the big three: heat, work, and internal energy. You’ll use the sign convention confidently, read work from a P–V diagram as area under the curve, and apply the first law \(Q = dU + W\) to constant-volume, constant-pressure, cyclic, and free-expansion processes. Isothermal and adiabatic changes are treated side by side, including their equations and the common confusion between them. Then kinetic theory makes gases feel logical: \(PV=nRT\) and \(PV=NkT\), assumptions, pressure from collisions, RMS speed, equipartition (linking \(C_v\), \(C_p\), and \(\gamma\)), and mean free path. Finally, you’ll connect the math of oscillations and waves—SHM equations, energy, spring and pendulum periods, progressive waves, superposition, standing waves on strings and in pipes, and beats—so you can translate descriptions into correct formulas fast.