Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Isha lohan 1
The best material you can have for mechanics is Concepts of Physics, Vol 1 by HC Verma. Solve the question from it's numerical exercise. If you get doubt in any ques, you can post it here on eduncle app. Also you can use the unit solved exercise of eduncle material and notes provided by eduncle. If you need more then the best authorized material is the book of HC Verma. Practice questions from there, if could not solve any one then ask for discussion.