Assuming asking for JEE Main, Solving problems of physics require good hold on basic concepts of physics (like work-energy theorem, Newton’s laws, etc).

Cracking physics in JEE requires systematic and well planned preparation strategy.

If you are starting a new chapter, never jump to questions until you have read the entire theory of the chapter from some good book. 

Try to have depth understanding of all the topics in your NCERT Physics Textbook.

Do practise as much you can to improve your subject.

Good Luck!