Hello Aditya,

If you like the book then eventually you will end up buying all the six parts of cengage. But I suggest you buy only those parts which includes the syllabus that is taught to you 11th standard. In 11th standard you are taught Mechanics and Heat Thermodynamics in physics.

So buy the first three parts ( Mechanics1, Mechanics2,  Waves and thermodynamics)

Rest of them you buy in your 12th standard since every year these books are updated.